diff --git a/e2e-tests/cypress/tests/integration/channels/channel_settings/channel_header_spec.ts b/e2e-tests/cypress/tests/integration/channels/channel_settings/channel_header_spec.ts
index 4fb91d9c3e1..9ddef7c5f0d 100644
--- a/e2e-tests/cypress/tests/integration/channels/channel_settings/channel_header_spec.ts
+++ b/e2e-tests/cypress/tests/integration/channels/channel_settings/channel_header_spec.ts
@@ -45,7 +45,7 @@ describe('Channel Settings', () => {
         });
 
         // # Create DM with admin and user 1
-        cy.apiCreateDirectChannel([user1.id, user1.id]).then(() => {
+        cy.apiCreateDirectChannel([admin.id, user1.id]).then(() => {
             // # Go to DM
             cy.visit(`/${testTeam.name}/messages/@${user1.username}`);
 
diff --git a/server/channels/api4/channel.go b/server/channels/api4/channel.go
index 3564ff4feef..0ef99b777bf 100644
--- a/server/channels/api4/channel.go
+++ b/server/channels/api4/channel.go
@@ -425,9 +425,18 @@ func restoreChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 }
 
 func createDirectChannel(c *Context, w http.ResponseWriter, r *http.Request) {
-	userIds := model.ArrayFromJSON(r.Body)
+	userIds, err := model.NonSortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("createDirectChannel", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	}
 	allowed := false
 
+	// single userId allowed if creating a self-channel
+	// NonSortedArrayFromJSON will remove duplicates, so need to add back
+	if len(userIds) == 1 && userIds[0] == c.AppContext.Session().UserId {
+		userIds = append(userIds, userIds[0])
+	}
 	if len(userIds) != 2 {
 		c.SetInvalidParam("user_ids")
 		return
@@ -464,9 +473,9 @@ func createDirectChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 
 	audit.AddEventParameter(auditRec, "user_id", otherUserId)
 
-	canSee, err := c.App.UserCanSeeOtherUser(c.AppContext, c.AppContext.Session().UserId, otherUserId)
-	if err != nil {
-		c.Err = err
+	canSee, appErr := c.App.UserCanSeeOtherUser(c.AppContext, c.AppContext.Session().UserId, otherUserId)
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
@@ -475,9 +484,9 @@ func createDirectChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	sc, err := c.App.GetOrCreateDirectChannel(c.AppContext, userIds[0], userIds[1])
-	if err != nil {
-		c.Err = err
+	sc, appErr := c.App.GetOrCreateDirectChannel(c.AppContext, userIds[0], userIds[1])
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
@@ -511,9 +520,11 @@ func searchGroupChannels(c *Context, w http.ResponseWriter, r *http.Request) {
 }
 
 func createGroupChannel(c *Context, w http.ResponseWriter, r *http.Request) {
-	userIds := model.ArrayFromJSON(r.Body)
-
-	if len(userIds) == 0 {
+	userIds, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("createGroupChannel", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	} else if len(userIds) == 0 {
 		c.SetInvalidParam("user_ids")
 		return
 	}
@@ -561,9 +572,9 @@ func createGroupChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	groupChannel, err := c.App.CreateGroupChannel(c.AppContext, userIds, c.AppContext.Session().UserId)
-	if err != nil {
-		c.Err = err
+	groupChannel, appErr := c.App.CreateGroupChannel(c.AppContext, userIds, c.AppContext.Session().UserId)
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
@@ -697,7 +708,12 @@ func getChannelsMemberCount(c *Context, w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	channelIDs := model.ArrayFromJSON(r.Body)
+	channelIDs, sortErr := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if sortErr != nil {
+		c.Err = model.NewAppError("getChannelsMemberCount", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(sortErr)
+		return
+	}
+
 	channels, err := c.App.GetChannels(c.AppContext, channelIDs)
 	if err != nil {
 		c.Err = err
@@ -711,10 +727,9 @@ func getChannelsMemberCount(c *Context, w http.ResponseWriter, r *http.Request)
 		}
 	}
 
-	channelsMemberCount, err := c.App.GetChannelsMemberCount(c.AppContext, channelIDs)
-
-	if err != nil {
-		c.Err = err
+	channelsMemberCount, appErr := c.App.GetChannelsMemberCount(c.AppContext, channelIDs)
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
@@ -899,8 +914,11 @@ func getPublicChannelsByIdsForTeam(c *Context, w http.ResponseWriter, r *http.Re
 		return
 	}
 
-	channelIds := model.ArrayFromJSON(r.Body)
-	if len(channelIds) == 0 {
+	channelIds, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("getPublicChannelsByIdsForTeam", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	} else if len(channelIds) == 0 {
 		c.SetInvalidParam("channel_ids")
 		return
 	}
@@ -917,15 +935,15 @@ func getPublicChannelsByIdsForTeam(c *Context, w http.ResponseWriter, r *http.Re
 		return
 	}
 
-	channels, err := c.App.GetPublicChannelsByIdsForTeam(c.AppContext, c.Params.TeamId, channelIds)
-	if err != nil {
-		c.Err = err
+	channels, appErr := c.App.GetPublicChannelsByIdsForTeam(c.AppContext, c.Params.TeamId, channelIds)
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
-	err = c.App.FillInChannelsProps(c.AppContext, channels)
-	if err != nil {
-		c.Err = err
+	appErr = c.App.FillInChannelsProps(c.AppContext, channels)
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
@@ -1439,8 +1457,11 @@ func getChannelMembersByIds(c *Context, w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	userIds := model.ArrayFromJSON(r.Body)
-	if len(userIds) == 0 {
+	userIds, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("getChannelMembersByIds", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	} else if len(userIds) == 0 {
 		c.SetInvalidParam("user_ids")
 		return
 	}
@@ -1450,9 +1471,9 @@ func getChannelMembersByIds(c *Context, w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	members, err := c.App.GetChannelMembersByIds(c.AppContext, c.Params.ChannelId, userIds)
-	if err != nil {
-		c.Err = err
+	members, appErr := c.App.GetChannelMembersByIds(c.AppContext, c.Params.ChannelId, userIds)
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
@@ -1562,14 +1583,16 @@ func viewChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 func readMultipleChannels(c *Context, w http.ResponseWriter, r *http.Request) {
 	c.RequireUserId()
 
-	var channelIDs []string
-	err := json.NewDecoder(r.Body).Decode(&channelIDs)
-	if err != nil || len(channelIDs) == 0 {
-		c.SetInvalidParamWithErr("channel_ids", err)
+	channelIds, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("readMultipleChannels", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	} else if len(channelIds) == 0 {
+		c.SetInvalidParam("channel_ids")
 		return
 	}
 
-	times, appErr := c.App.MarkChannelsAsViewed(c.AppContext, channelIDs, c.Params.UserId, c.AppContext.Session().Id, true, c.App.IsCRTEnabledForUser(c.AppContext, c.Params.UserId))
+	times, appErr := c.App.MarkChannelsAsViewed(c.AppContext, channelIds, c.Params.UserId, c.AppContext.Session().Id, true, c.App.IsCRTEnabledForUser(c.AppContext, c.Params.UserId))
 	if appErr != nil {
 		c.Err = appErr
 		return
diff --git a/server/channels/api4/channel_category.go b/server/channels/api4/channel_category.go
index 5401bc6703d..c3e8c27b475 100644
--- a/server/channels/api4/channel_category.go
+++ b/server/channels/api4/channel_category.go
@@ -118,7 +118,11 @@ func updateCategoryOrderForTeamForUser(c *Context, w http.ResponseWriter, r *htt
 	auditRec := c.MakeAuditRecord("updateCategoryOrderForTeamForUser", audit.Fail)
 	defer c.LogAuditRec(auditRec)
 
-	categoryOrder := model.ArrayFromJSON(r.Body)
+	categoryOrder, err := model.NonSortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("updateCategoryOrderForTeamForUser", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	}
 
 	for _, categoryId := range categoryOrder {
 		if !c.App.SessionHasPermissionToCategory(c.AppContext, *c.AppContext.Session(), c.Params.UserId, c.Params.TeamId, categoryId) {
@@ -127,9 +131,9 @@ func updateCategoryOrderForTeamForUser(c *Context, w http.ResponseWriter, r *htt
 		}
 	}
 
-	err := c.App.UpdateSidebarCategoryOrder(c.AppContext, c.Params.UserId, c.Params.TeamId, categoryOrder)
-	if err != nil {
-		c.Err = err
+	appErr := c.App.UpdateSidebarCategoryOrder(c.AppContext, c.Params.UserId, c.Params.TeamId, categoryOrder)
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
diff --git a/server/channels/api4/data_retention.go b/server/channels/api4/data_retention.go
index 64d7053e234..3393fccf86a 100644
--- a/server/channels/api4/data_retention.go
+++ b/server/channels/api4/data_retention.go
@@ -264,10 +264,9 @@ func searchTeamsInPolicy(c *Context, w http.ResponseWriter, r *http.Request) {
 func addTeamsToPolicy(c *Context, w http.ResponseWriter, r *http.Request) {
 	c.RequirePolicyId()
 	policyId := c.Params.PolicyId
-	var teamIDs []string
-	jsonErr := json.NewDecoder(r.Body).Decode(&teamIDs)
-	if jsonErr != nil {
-		c.SetInvalidParamWithErr("team_ids", jsonErr)
+	teamIDs, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("addTeamsToPolicy", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
 		return
 	}
 	auditRec := c.MakeAuditRecord("addTeamsToPolicy", audit.Fail)
@@ -279,9 +278,9 @@ func addTeamsToPolicy(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	err := c.App.AddTeamsToRetentionPolicy(policyId, teamIDs)
-	if err != nil {
-		c.Err = err
+	appErr := c.App.AddTeamsToRetentionPolicy(policyId, teamIDs)
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
@@ -292,10 +291,9 @@ func addTeamsToPolicy(c *Context, w http.ResponseWriter, r *http.Request) {
 func removeTeamsFromPolicy(c *Context, w http.ResponseWriter, r *http.Request) {
 	c.RequirePolicyId()
 	policyId := c.Params.PolicyId
-	var teamIDs []string
-	jsonErr := json.NewDecoder(r.Body).Decode(&teamIDs)
-	if jsonErr != nil {
-		c.SetInvalidParamWithErr("team_ids", jsonErr)
+	teamIDs, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("removeTeamsFromPolicy", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
 		return
 	}
 	auditRec := c.MakeAuditRecord("removeTeamsFromPolicy", audit.Fail)
@@ -308,9 +306,9 @@ func removeTeamsFromPolicy(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	err := c.App.RemoveTeamsFromRetentionPolicy(policyId, teamIDs)
-	if err != nil {
-		c.Err = err
+	appErr := c.App.RemoveTeamsFromRetentionPolicy(policyId, teamIDs)
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
@@ -385,10 +383,9 @@ func searchChannelsInPolicy(c *Context, w http.ResponseWriter, r *http.Request)
 func addChannelsToPolicy(c *Context, w http.ResponseWriter, r *http.Request) {
 	c.RequirePolicyId()
 	policyId := c.Params.PolicyId
-	var channelIDs []string
-	jsonErr := json.NewDecoder(r.Body).Decode(&channelIDs)
-	if jsonErr != nil {
-		c.SetInvalidParamWithErr("channel_ids", jsonErr)
+	channelIDs, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("addChannelsToPolicy", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
 		return
 	}
 	auditRec := c.MakeAuditRecord("addChannelsToPolicy", audit.Fail)
@@ -401,9 +398,9 @@ func addChannelsToPolicy(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	err := c.App.AddChannelsToRetentionPolicy(policyId, channelIDs)
-	if err != nil {
-		c.Err = err
+	appErr := c.App.AddChannelsToRetentionPolicy(policyId, channelIDs)
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
@@ -414,10 +411,9 @@ func addChannelsToPolicy(c *Context, w http.ResponseWriter, r *http.Request) {
 func removeChannelsFromPolicy(c *Context, w http.ResponseWriter, r *http.Request) {
 	c.RequirePolicyId()
 	policyId := c.Params.PolicyId
-	var channelIDs []string
-	jsonErr := json.NewDecoder(r.Body).Decode(&channelIDs)
-	if jsonErr != nil {
-		c.SetInvalidParamWithErr("channel_ids", jsonErr)
+	channelIDs, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("removeChannelsFromPolicy", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
 		return
 	}
 	auditRec := c.MakeAuditRecord("removeChannelsFromPolicy", audit.Fail)
@@ -430,9 +426,9 @@ func removeChannelsFromPolicy(c *Context, w http.ResponseWriter, r *http.Request
 		return
 	}
 
-	err := c.App.RemoveChannelsFromRetentionPolicy(policyId, channelIDs)
-	if err != nil {
-		c.Err = err
+	appErr := c.App.RemoveChannelsFromRetentionPolicy(policyId, channelIDs)
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
diff --git a/server/channels/api4/emoji.go b/server/channels/api4/emoji.go
index 4d292675123..33ec728af2e 100644
--- a/server/channels/api4/emoji.go
+++ b/server/channels/api4/emoji.go
@@ -240,8 +240,11 @@ func getEmojiByName(c *Context, w http.ResponseWriter, r *http.Request) {
 }
 
 func getEmojisByNames(c *Context, w http.ResponseWriter, r *http.Request) {
-	names := model.ArrayFromJSON(r.Body)
-	if len(names) == 0 {
+	names, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("getEmojisByNames", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	} else if len(names) == 0 {
 		c.SetInvalidParam("names")
 		return
 	}
@@ -258,9 +261,9 @@ func getEmojisByNames(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	emojis, err := c.App.GetMultipleEmojiByName(c.AppContext, names)
-	if err != nil {
-		c.Err = err
+	emojis, appErr := c.App.GetMultipleEmojiByName(c.AppContext, names)
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
diff --git a/server/channels/api4/emoji_test.go b/server/channels/api4/emoji_test.go
index fcfe58519f1..b9d604824d0 100644
--- a/server/channels/api4/emoji_test.go
+++ b/server/channels/api4/emoji_test.go
@@ -316,25 +316,34 @@ func TestGetEmojisByNames(t *testing.T) {
 	t.Run("should return multiple emojis", func(t *testing.T) {
 		emojis, _, err := client.GetEmojisByNames(context.Background(), []string{emoji1.Name, emoji2.Name})
 
+		var emojiIds []string
+		for _, emoji := range emojis {
+			emojiIds = append(emojiIds, emoji.Id)
+		}
+
 		require.NoError(t, err)
 		require.Len(t, emojis, 2)
-		assert.Equal(t, emoji1.Id, emojis[0].Id)
-		assert.Equal(t, emoji2.Id, emojis[1].Id)
+		assert.Contains(t, emojiIds, emoji1.Id)
+		assert.Contains(t, emojiIds, emoji2.Id)
 	})
 
 	t.Run("should ignore non-existent emojis", func(t *testing.T) {
 		emojis, _, err := client.GetEmojisByNames(context.Background(), []string{emoji1.Name, emoji2.Name, model.NewId()})
+		var emojiIds []string
+		for _, emoji := range emojis {
+			emojiIds = append(emojiIds, emoji.Id)
+		}
 
 		require.NoError(t, err)
 		require.Len(t, emojis, 2)
-		assert.Equal(t, emoji1.Id, emojis[0].Id)
-		assert.Equal(t, emoji2.Id, emojis[1].Id)
+		assert.Contains(t, emojiIds, emoji1.Id)
+		assert.Contains(t, emojiIds, emoji2.Id)
 	})
 
 	t.Run("should return an error when too many emojis are requested", func(t *testing.T) {
 		names := make([]string, GetEmojisByNamesMax+1)
 		for i := 0; i < len(names); i++ {
-			names[i] = emoji1.Name
+			names[i] = model.NewId()
 		}
 
 		_, _, err := client.GetEmojisByNames(context.Background(), names)
diff --git a/server/channels/api4/post.go b/server/channels/api4/post.go
index 090c195cbd0..54754fa352b 100644
--- a/server/channels/api4/post.go
+++ b/server/channels/api4/post.go
@@ -504,9 +504,11 @@ func getPost(c *Context, w http.ResponseWriter, r *http.Request) {
 
 // getPostsByIds also sets a header to indicate, if posts were truncated as per the cloud plan's limit.
 func getPostsByIds(c *Context, w http.ResponseWriter, r *http.Request) {
-	postIDs := model.ArrayFromJSON(r.Body)
-
-	if len(postIDs) == 0 {
+	postIDs, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("getPostsByIds", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	} else if len(postIDs) == 0 {
 		c.SetInvalidParam("post_ids")
 		return
 	}
@@ -516,9 +518,9 @@ func getPostsByIds(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	postsList, firstInaccessiblePostTime, err := c.App.GetPostsByIds(postIDs)
-	if err != nil {
-		c.Err = err
+	postsList, firstInaccessiblePostTime, appErr := c.App.GetPostsByIds(postIDs)
+	if appErr != nil {
+		c.Err = appErr
 		return
 	}
 
@@ -530,9 +532,9 @@ func getPostsByIds(c *Context, w http.ResponseWriter, r *http.Request) {
 		if val, ok := channelMap[post.ChannelId]; ok {
 			channel = val
 		} else {
-			channel, err = c.App.GetChannel(c.AppContext, post.ChannelId)
-			if err != nil {
-				c.Err = err
+			channel, appErr = c.App.GetChannel(c.AppContext, post.ChannelId)
+			if appErr != nil {
+				c.Err = appErr
 				return
 			}
 			channelMap[channel.Id] = channel
diff --git a/server/channels/api4/reaction.go b/server/channels/api4/reaction.go
index e0cf409a3d3..0c4d555fbc1 100644
--- a/server/channels/api4/reaction.go
+++ b/server/channels/api4/reaction.go
@@ -119,7 +119,11 @@ func deleteReaction(c *Context, w http.ResponseWriter, r *http.Request) {
 }
 
 func getBulkReactions(c *Context, w http.ResponseWriter, r *http.Request) {
-	postIds := model.ArrayFromJSON(r.Body)
+	postIds, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("getBulkReactions", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	}
 	for _, postId := range postIds {
 		if !c.App.SessionHasPermissionToChannelByPost(*c.AppContext.Session(), postId, model.PermissionReadChannelContent) {
 			c.SetPermissionError(model.PermissionReadChannelContent)
diff --git a/server/channels/api4/role.go b/server/channels/api4/role.go
index ba499fe09c1..6be42aab4a3 100644
--- a/server/channels/api4/role.go
+++ b/server/channels/api4/role.go
@@ -84,9 +84,11 @@ func getRoleByName(c *Context, w http.ResponseWriter, r *http.Request) {
 }
 
 func getRolesByNames(c *Context, w http.ResponseWriter, r *http.Request) {
-	rolenames := model.ArrayFromJSON(r.Body)
-
-	if len(rolenames) == 0 {
+	rolenames, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("getRolesByNames", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	} else if len(rolenames) == 0 {
 		c.SetInvalidParam("rolenames")
 		return
 	}
diff --git a/server/channels/api4/role_test.go b/server/channels/api4/role_test.go
index dfcea31ee34..7cdcd27cca6 100644
--- a/server/channels/api4/role_test.go
+++ b/server/channels/api4/role_test.go
@@ -5,6 +5,7 @@ package api4
 
 import (
 	"context"
+	"fmt"
 	"sort"
 	"strings"
 	"testing"
@@ -189,7 +190,7 @@ func TestGetRolesByNames(t *testing.T) {
 		// too many roles should error with bad request
 		roles := []string{}
 		for i := 0; i < GetRolesByNamesMax+10; i++ {
-			roles = append(roles, role1.Name)
+			roles = append(roles, fmt.Sprintf("role1.Name%v", i))
 		}
 
 		_, resp, err := client.GetRolesByNames(context.Background(), roles)
diff --git a/server/channels/api4/status.go b/server/channels/api4/status.go
index 124ab3d3b86..921fea718fa 100644
--- a/server/channels/api4/status.go
+++ b/server/channels/api4/status.go
@@ -49,9 +49,11 @@ func getUserStatus(c *Context, w http.ResponseWriter, r *http.Request) {
 }
 
 func getUserStatusesByIds(c *Context, w http.ResponseWriter, r *http.Request) {
-	userIds := model.ArrayFromJSON(r.Body)
-
-	if len(userIds) == 0 {
+	userIds, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("getUserStatusesByIds", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	} else if len(userIds) == 0 {
 		c.SetInvalidParam("user_ids")
 		return
 	}
diff --git a/server/channels/api4/system.go b/server/channels/api4/system.go
index a220ba832fc..49f3feadd9d 100644
--- a/server/channels/api4/system.go
+++ b/server/channels/api4/system.go
@@ -967,7 +967,11 @@ func updateViewedProductNotices(c *Context, w http.ResponseWriter, r *http.Reque
 	defer c.LogAuditRec(auditRec)
 	c.LogAudit("attempt")
 
-	ids := model.ArrayFromJSON(r.Body)
+	ids, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("updateViewedProductNotices", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	}
 	appErr := c.App.UpdateViewedProductNotices(c.AppContext.Session().UserId, ids)
 	if appErr != nil {
 		c.Err = appErr
diff --git a/server/channels/api4/team.go b/server/channels/api4/team.go
index 8c6ac8e9ec7..1a568d4e15e 100644
--- a/server/channels/api4/team.go
+++ b/server/channels/api4/team.go
@@ -644,10 +644,12 @@ func getTeamMembersByIds(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	var userIDs []string
-	err := json.NewDecoder(r.Body).Decode(&userIDs)
-	if err != nil || len(userIDs) == 0 {
-		c.SetInvalidParamWithErr("user_ids", err)
+	userIDs, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("getTeamMembersByIds", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	} else if len(userIDs) == 0 {
+		c.SetInvalidParam("user_ids")
 		return
 	}
 
diff --git a/server/channels/api4/user.go b/server/channels/api4/user.go
index 3c1dfff7388..307b04ddabd 100644
--- a/server/channels/api4/user.go
+++ b/server/channels/api4/user.go
@@ -623,9 +623,11 @@ func getFilteredUsersStats(c *Context, w http.ResponseWriter, r *http.Request) {
 }
 
 func getUsersByGroupChannelIds(c *Context, w http.ResponseWriter, r *http.Request) {
-	channelIds := model.ArrayFromJSON(r.Body)
-
-	if len(channelIds) == 0 {
+	channelIds, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil || len(channelIds) == 0 {
+		c.Err = model.NewAppError("getUsersByGroupChannelIds", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	} else if len(channelIds) == 0 {
 		c.SetInvalidParam("channel_ids")
 		return
 	}
@@ -636,7 +638,7 @@ func getUsersByGroupChannelIds(c *Context, w http.ResponseWriter, r *http.Reques
 		return
 	}
 
-	err := json.NewEncoder(w).Encode(usersByChannelId)
+	err = json.NewEncoder(w).Encode(usersByChannelId)
 	if err != nil {
 		c.Logger.Warn("Error writing response", mlog.Err(err))
 	}
@@ -953,17 +955,15 @@ func requireGroupAccess(c *web.Context, groupID string) *model.AppError {
 }
 
 func getUsersByIds(c *Context, w http.ResponseWriter, r *http.Request) {
-	var userIDs []string
-	err := json.NewDecoder(r.Body).Decode(&userIDs)
-	if err != nil || len(userIDs) == 0 {
-		c.SetInvalidParamWithErr("user_ids", err)
+	userIDs, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("getUsersByIds", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	} else if len(userIDs) == 0 {
+		c.SetInvalidParam("user_ids")
 		return
 	}
 
-	// we remove the duplicate IDs as it can bring a significant load to the
-	// database.
-	userIDs = model.RemoveDuplicateStrings(userIDs)
-
 	sinceString := r.URL.Query().Get("since")
 
 	options := &store.UserGetByIdsOpts{
@@ -1002,10 +1002,12 @@ func getUsersByIds(c *Context, w http.ResponseWriter, r *http.Request) {
 }
 
 func getUsersByNames(c *Context, w http.ResponseWriter, r *http.Request) {
-	var usernames []string
-	err := json.NewDecoder(r.Body).Decode(&usernames)
-	if err != nil || len(usernames) == 0 {
-		c.SetInvalidParamWithErr("usernames", err)
+	usernames, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("getUsersByNames", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	} else if len(usernames) == 0 {
+		c.SetInvalidParam("usernames")
 		return
 	}
 
diff --git a/server/channels/api4/user_local.go b/server/channels/api4/user_local.go
index 2171d14f7cd..cf7ffac59b1 100644
--- a/server/channels/api4/user_local.go
+++ b/server/channels/api4/user_local.go
@@ -233,17 +233,15 @@ func localGetUsers(c *Context, w http.ResponseWriter, r *http.Request) {
 }
 
 func localGetUsersByIds(c *Context, w http.ResponseWriter, r *http.Request) {
-	userIDs := model.ArrayFromJSON(r.Body)
-
-	if len(userIDs) == 0 {
+	userIDs, err := model.SortedArrayFromJSON(r.Body, *c.App.Config().ServiceSettings.MaximumPayloadSizeBytes)
+	if err != nil {
+		c.Err = model.NewAppError("localGetUsersByIds", model.PayloadParseError, nil, "", http.StatusBadRequest).Wrap(err)
+		return
+	} else if len(userIDs) == 0 {
 		c.SetInvalidParam("user_ids")
 		return
 	}
 
-	// we remove the duplicate IDs as it can bring a significant load to the
-	// database.
-	userIDs = model.RemoveDuplicateStrings(userIDs)
-
 	sinceString := r.URL.Query().Get("since")
 
 	options := &store.UserGetByIdsOpts{
@@ -251,9 +249,9 @@ func localGetUsersByIds(c *Context, w http.ResponseWriter, r *http.Request) {
 	}
 
 	if sinceString != "" {
-		since, err := strconv.ParseInt(sinceString, 10, 64)
-		if err != nil {
-			c.SetInvalidParamWithErr("since", err)
+		since, parseErr := strconv.ParseInt(sinceString, 10, 64)
+		if parseErr != nil {
+			c.SetInvalidParamWithErr("since", parseErr)
 			return
 		}
 		options.Since = since
diff --git a/server/i18n/en.json b/server/i18n/en.json
index 4223c820022..2813cbb21d4 100644
--- a/server/i18n/en.json
+++ b/server/i18n/en.json
@@ -2376,6 +2376,10 @@
     "id": "api.outgoing_webhook.disabled.app_error",
     "translation": "Outgoing webhooks have been disabled by the system admin."
   },
+  {
+    "id": "api.payload.parse.error",
+    "translation": "An error occurred while parsing the payload."
+  },
   {
     "id": "api.plugin.install.download_failed.app_error",
     "translation": "An error occurred while downloading the plugin."
@@ -8926,6 +8930,10 @@
     "id": "model.config.is_valid.max_notify_per_channel.app_error",
     "translation": "Invalid maximum notifications per channel for team settings. Must be a positive number."
   },
+  {
+    "id": "model.config.is_valid.max_payload_size.app_error",
+    "translation": "Invalid max payload size for service settings. Must be a whole number greater than zero."
+  },
   {
     "id": "model.config.is_valid.max_users.app_error",
     "translation": "Invalid maximum users per team for team settings. Must be a positive number."
diff --git a/server/platform/services/telemetry/telemetry.go b/server/platform/services/telemetry/telemetry.go
index 1598d9e0127..7fe795861d4 100644
--- a/server/platform/services/telemetry/telemetry.go
+++ b/server/platform/services/telemetry/telemetry.go
@@ -495,6 +495,7 @@ func (ts *TelemetryService) trackConfig() {
 		"self_hosted_purchase":                                    *cfg.ServiceSettings.SelfHostedPurchase,
 		"allow_synced_drafts":                                     *cfg.ServiceSettings.AllowSyncedDrafts,
 		"refresh_post_stats_run_time":                             *cfg.ServiceSettings.RefreshPostStatsRunTime,
+		"maximum_payload_size":                                    *cfg.ServiceSettings.MaximumPayloadSizeBytes,
 	})
 
 	ts.SendTelemetry(TrackConfigTeam, map[string]any{
diff --git a/server/public/model/client4.go b/server/public/model/client4.go
index 08ef2ac0ad2..6cfa9b4eaae 100644
--- a/server/public/model/client4.go
+++ b/server/public/model/client4.go
@@ -103,6 +103,15 @@ func (c *Client4) boolString(value bool) string {
 	return "false"
 }
 
+func (c *Client4) ArrayFromJSON(data io.Reader) []string {
+	var objmap []string
+	json.NewDecoder(data).Decode(&objmap)
+	if objmap == nil {
+		return make([]string, 0)
+	}
+	return objmap
+}
+
 func closeBody(r *http.Response) {
 	if r.Body != nil {
 		_, _ = io.Copy(io.Discard, r.Body)
@@ -3136,7 +3145,7 @@ func (c *Client4) GetChannelMembersTimezones(ctx context.Context, channelId stri
 		return nil, BuildResponse(r), err
 	}
 	defer closeBody(r)
-	return ArrayFromJSON(r.Body), BuildResponse(r), nil
+	return c.ArrayFromJSON(r.Body), BuildResponse(r), nil
 }
 
 // GetPinnedPosts gets a list of pinned posts.
@@ -5818,7 +5827,7 @@ func (c *Client4) GetLogs(ctx context.Context, page, perPage int) ([]string, *Re
 		return nil, BuildResponse(r), err
 	}
 	defer closeBody(r)
-	return ArrayFromJSON(r.Body), BuildResponse(r), nil
+	return c.ArrayFromJSON(r.Body), BuildResponse(r), nil
 }
 
 // PostLog is a convenience Web Service call so clients can log messages into
@@ -7922,7 +7931,7 @@ func (c *Client4) GetSidebarCategoryOrderForTeamForUser(ctx context.Context, use
 		return nil, BuildResponse(r), err
 	}
 	defer closeBody(r)
-	return ArrayFromJSON(r.Body), BuildResponse(r), nil
+	return c.ArrayFromJSON(r.Body), BuildResponse(r), nil
 }
 
 func (c *Client4) UpdateSidebarCategoryOrderForTeamForUser(ctx context.Context, userID, teamID string, order []string) ([]string, *Response, error) {
@@ -7936,7 +7945,7 @@ func (c *Client4) UpdateSidebarCategoryOrderForTeamForUser(ctx context.Context,
 		return nil, BuildResponse(r), err
 	}
 	defer closeBody(r)
-	return ArrayFromJSON(r.Body), BuildResponse(r), nil
+	return c.ArrayFromJSON(r.Body), BuildResponse(r), nil
 }
 
 func (c *Client4) GetSidebarCategoryForTeamForUser(ctx context.Context, userID, teamID, categoryID, etag string) (*SidebarCategoryWithChannels, *Response, error) {
@@ -8396,7 +8405,7 @@ func (c *Client4) ListImports(ctx context.Context) ([]string, *Response, error)
 		return nil, BuildResponse(r), err
 	}
 	defer closeBody(r)
-	return ArrayFromJSON(r.Body), BuildResponse(r), nil
+	return c.ArrayFromJSON(r.Body), BuildResponse(r), nil
 }
 
 func (c *Client4) ListExports(ctx context.Context) ([]string, *Response, error) {
@@ -8405,7 +8414,7 @@ func (c *Client4) ListExports(ctx context.Context) ([]string, *Response, error)
 		return nil, BuildResponse(r), err
 	}
 	defer closeBody(r)
-	return ArrayFromJSON(r.Body), BuildResponse(r), nil
+	return c.ArrayFromJSON(r.Body), BuildResponse(r), nil
 }
 
 func (c *Client4) DeleteExport(ctx context.Context, name string) (*Response, error) {
diff --git a/server/public/model/config.go b/server/public/model/config.go
index 06226ccb254..ec889947708 100644
--- a/server/public/model/config.go
+++ b/server/public/model/config.go
@@ -402,6 +402,7 @@ type ServiceSettings struct {
 	AllowSyncedDrafts                                 *bool   `access:"site_posts"`
 	UniqueEmojiReactionLimitPerPost                   *int    `access:"site_posts"`
 	RefreshPostStatsRunTime                           *string `access:"site_users_and_teams"`
+	MaximumPayloadSizeBytes                           *int64  `access:"environment_file_storage,write_restrictable,cloud_restrictable"`
 }
 
 var MattermostGiphySdkKey string
@@ -908,6 +909,10 @@ func (s *ServiceSettings) SetDefaults(isUpdate bool) {
 	if s.RefreshPostStatsRunTime == nil {
 		s.RefreshPostStatsRunTime = NewString("00:00")
 	}
+
+	if s.MaximumPayloadSizeBytes == nil {
+		s.MaximumPayloadSizeBytes = NewInt64(100000)
+	}
 }
 
 type ClusterSettings struct {
@@ -3978,6 +3983,10 @@ func (s *ServiceSettings) isValid() *AppError {
 		}
 	}
 
+	if *s.MaximumPayloadSizeBytes <= 0 {
+		return NewAppError("Config.IsValid", "model.config.is_valid.max_payload_size.app_error", nil, "", http.StatusBadRequest)
+	}
+
 	if *s.ReadTimeout <= 0 {
 		return NewAppError("Config.IsValid", "model.config.is_valid.read_timeout.app_error", nil, "", http.StatusBadRequest)
 	}
diff --git a/server/public/model/utils.go b/server/public/model/utils.go
index 01559feabff..aac53e6b9a2 100644
--- a/server/public/model/utils.go
+++ b/server/public/model/utils.go
@@ -29,13 +29,14 @@ import (
 )
 
 const (
-	LowercaseLetters = "abcdefghijklmnopqrstuvwxyz"
-	UppercaseLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
-	NUMBERS          = "0123456789"
-	SYMBOLS          = " !\"\\#$%&'()*+,-./:;<=>?@[]^_`|~"
-	BinaryParamKey   = "MM_BINARY_PARAMETERS"
-	NoTranslation    = "<untranslated>"
-	maxPropSizeBytes = 1024 * 1024
+	LowercaseLetters  = "abcdefghijklmnopqrstuvwxyz"
+	UppercaseLetters  = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	NUMBERS           = "0123456789"
+	SYMBOLS           = " !\"\\#$%&'()*+,-./:;<=>?@[]^_`|~"
+	BinaryParamKey    = "MM_BINARY_PARAMETERS"
+	NoTranslation     = "<untranslated>"
+	maxPropSizeBytes  = 1024 * 1024
+	PayloadParseError = "api.payload.parse.error"
 )
 
 var ErrMaxPropSizeExceeded = fmt.Errorf("max prop size of %d exceeded", maxPropSizeBytes)
@@ -484,17 +485,41 @@ func ArrayToJSON(objmap []string) string {
 	return string(b)
 }
 
+// Deprecated: ArrayFromJSON is deprecated,
+// use SortedArrayFromJSON or NonSortedArrayFromJSON instead
 func ArrayFromJSON(data io.Reader) []string {
 	var objmap []string
-
 	json.NewDecoder(data).Decode(&objmap)
 	if objmap == nil {
 		return make([]string, 0)
 	}
-
 	return objmap
 }
 
+func SortedArrayFromJSON(data io.Reader, maxBytes int64) ([]string, error) {
+	var obj []string
+	lr := io.LimitReader(data, maxBytes)
+	err := json.NewDecoder(lr).Decode(&obj)
+	if err != nil || obj == nil {
+		return nil, err
+	}
+
+	// Remove duplicate IDs as it can bring a significant load to the database.
+	return RemoveDuplicateStrings(obj), nil
+}
+
+func NonSortedArrayFromJSON(data io.Reader, maxBytes int64) ([]string, error) {
+	var obj []string
+	lr := io.LimitReader(data, maxBytes)
+	err := json.NewDecoder(lr).Decode(&obj)
+	if err != nil || obj == nil {
+		return nil, err
+	}
+
+	// Remove duplicate IDs, but don't sort.
+	return RemoveDuplicateStringsNonSort(obj), nil
+}
+
 func ArrayFromInterface(data any) []string {
 	stringArray := []string{}
 
@@ -737,6 +762,20 @@ func RemoveDuplicateStrings(in []string) []string {
 	return in[:j+1]
 }
 
+// RemoveDuplicateStringsNonSort does a removal of duplicate
+// strings using a map.
+func RemoveDuplicateStringsNonSort(in []string) []string {
+	allKeys := make(map[string]bool)
+	list := []string{}
+	for _, item := range in {
+		if _, value := allKeys[item]; !value {
+			allKeys[item] = true
+			list = append(list, item)
+		}
+	}
+	return list
+}
+
 func GetPreferredTimezone(timezone StringMap) string {
 	if timezone["useAutomaticTimezone"] == "true" {
 		return timezone["automaticTimezone"]
diff --git a/server/public/model/utils_test.go b/server/public/model/utils_test.go
index d2ac34dca36..61958df67f0 100644
--- a/server/public/model/utils_test.go
+++ b/server/public/model/utils_test.go
@@ -5,8 +5,10 @@ package model
 
 import (
 	"bytes"
+	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"net/http"
 	"reflect"
 	"strings"
@@ -200,6 +202,88 @@ func TestMapJson(t *testing.T) {
 	require.LessOrEqual(t, len(rm2), 0, "make should be invalid")
 }
 
+func TestSortedArrayFromJSON(t *testing.T) {
+	t.Run("Successful parse", func(t *testing.T) {
+		ids := []string{NewId(), NewId(), NewId()}
+		b, _ := json.Marshal(ids)
+		a, err := SortedArrayFromJSON(bytes.NewReader(b), 1000)
+		require.NoError(t, err)
+		require.ElementsMatch(t, ids, a)
+	})
+
+	t.Run("Empty Array", func(t *testing.T) {
+		ids := []string{}
+		b, _ := json.Marshal(ids)
+		a, err := SortedArrayFromJSON(bytes.NewReader(b), 1000)
+		require.NoError(t, err)
+		require.Empty(t, a)
+	})
+
+	t.Run("Error too large", func(t *testing.T) {
+		var ids []string
+		for i := 0; i <= 100; i++ {
+			ids = append(ids, NewId())
+		}
+		b, _ := json.Marshal(ids)
+		_, err := SortedArrayFromJSON(bytes.NewReader(b), 1000)
+		require.Error(t, err)
+		require.ErrorIs(t, err, io.ErrUnexpectedEOF)
+	})
+
+	t.Run("Duplicate keys, returns one", func(t *testing.T) {
+		var ids []string
+		id := NewId()
+		for i := 0; i < 10; i++ {
+			ids = append(ids, id)
+		}
+		b, _ := json.Marshal(ids)
+		a, err := SortedArrayFromJSON(bytes.NewReader(b), 26000)
+		require.NoError(t, err)
+		require.Len(t, a, 1)
+	})
+}
+
+func TestNonSortedArrayFromJSON(t *testing.T) {
+	t.Run("Successful parse", func(t *testing.T) {
+		ids := []string{NewId(), NewId(), NewId()}
+		b, _ := json.Marshal(ids)
+		a, err := NonSortedArrayFromJSON(bytes.NewReader(b), 1000)
+		require.NoError(t, err)
+		require.Equal(t, ids, a)
+	})
+
+	t.Run("Empty Array", func(t *testing.T) {
+		ids := []string{}
+		b, _ := json.Marshal(ids)
+		a, err := NonSortedArrayFromJSON(bytes.NewReader(b), 1000)
+		require.NoError(t, err)
+		require.Empty(t, a)
+	})
+
+	t.Run("Error too large", func(t *testing.T) {
+		var ids []string
+		for i := 0; i <= 100; i++ {
+			ids = append(ids, NewId())
+		}
+		b, _ := json.Marshal(ids)
+		_, err := NonSortedArrayFromJSON(bytes.NewReader(b), 1000)
+		require.Error(t, err)
+		require.ErrorIs(t, err, io.ErrUnexpectedEOF)
+	})
+
+	t.Run("Duplicate keys, returns one", func(t *testing.T) {
+		var ids []string
+		id := NewId()
+		for i := 0; i <= 10; i++ {
+			ids = append(ids, id)
+		}
+		b, _ := json.Marshal(ids)
+		a, err := NonSortedArrayFromJSON(bytes.NewReader(b), 26000)
+		require.NoError(t, err)
+		require.Len(t, a, 1)
+	})
+}
+
 func TestIsValidEmail(t *testing.T) {
 	for _, testCase := range []struct {
 		Input    string
diff --git a/tools/mmgotool/commands/i18n.go b/tools/mmgotool/commands/i18n.go
index 450140516d3..909028e21bf 100644
--- a/tools/mmgotool/commands/i18n.go
+++ b/tools/mmgotool/commands/i18n.go
@@ -466,6 +466,7 @@ func extractForConstants(name string, valueNode ast.Expr) *string {
 		"ExpiredLicenseError":          true,
 		"InvalidLicenseError":          true,
 		"NoTranslation":                true,
+		"PayloadParseError":            true,
 	}
 
 	if _, ok := validConstants[name]; !ok {