diff --git a/doc/configuration.txt b/doc/configuration.txt
index 8552d0e23..2f1e57e44 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -185,7 +185,7 @@ waiting for new requests, just as if it was a keep-alive HTTP connection.
 HAProxy supports 4 connection modes :
   - keep alive    : all requests and responses are processed (default)
   - tunnel        : only the first request and response are processed,
-                    everything else is forwarded with no analysis.
+                    everything else is forwarded with no analysis (deprecated).
   - server close  : the server-facing connection is closed after the response.
   - close         : the connection is actively closed after end of response.
 
@@ -2047,8 +2047,10 @@ the backend's. HAProxy supports 4 connection modes :
   - TUN: tunnel ("option http-tunnel") : this was the default mode for versions
     1.0 to 1.5-dev21 : only the first request and response are processed, and
     everything else is forwarded with no analysis at all. This mode should not
-    be used as it creates lots of trouble with logging and HTTP processing. It
-    is supported only on frontends.
+    be used as it creates lots of trouble with logging and HTTP processing.
+    And because it cannot work in HTTP/2, this option is deprecated and it is
+    only supported on legacy HTTP frontends. In HTX, it is ignored and a
+    warning is emitted during HAProxy startup.
 
   - SCL: server close ("option http-server-close") : the server-facing
     connection is closed after the end of the response is received, but the
@@ -2166,7 +2168,7 @@ option http-keep-alive               (*)  X          X         X         X
 option http-no-delay                 (*)  X          X         X         X
 option http-pretend-keepalive        (*)  X          -         X         X
 option http-server-close             (*)  X          X         X         X
-option http-tunnel                   (*)  X          X         X         -
+option http-tunnel      (deprecated) (*)  X          X         X         -
 option http-use-proxy-header         (*)  X          X         X         -
 option http-use-htx                  (*)  X          X         X         X
 option httpchk                            X          -         X         X
@@ -6145,13 +6147,17 @@ no option http-server-close
              "option http-keep-alive", and "1.1. The HTTP transaction model".
 
 
-option http-tunnel
-no option http-tunnel
-  Disable or enable HTTP connection processing after first transaction
+option http-tunnel    (deprecated)
+no option http-tunnel (deprecated)
+  Disable or enable HTTP connection processing after first transaction.
   May be used in sections :   defaults | frontend | listen | backend
                                  yes   |    yes   |   yes  |   no
   Arguments : none
 
+  Warning : Because it cannot work in HTTP/2, this option is deprecated and it
+  is only supported on legacy HTTP frontends. In HTX, it is ignored and a
+  warning is emitted during HAProxy startup.
+
   By default HAProxy operates in keep-alive mode with regards to persistent
   connections: for each connection it processes each request and response, and
   leaves the connection idle on both sides between the end of a response and
diff --git a/src/cfgparse.c b/src/cfgparse.c
index 495a25ba2..ffff9cc6b 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -3539,6 +3539,16 @@ out_uri_auth_compat:
 			newsrv->mux_proto = mux_ent;
 		}
 
+		/* the option "http-tunnel" is ignored when HTX is enabled and
+		 * only works with the legacy HTTP. So emit a warning if the
+		 * option is set on a HTX frontend. */
+		if ((curproxy->cap & PR_CAP_FE) && curproxy->options2 & PR_O2_USE_HTX &&
+		    (curproxy->options & PR_O_HTTP_MODE) == PR_O_HTTP_TUN) {
+			ha_warning("config : %s '%s' : the option 'http-tunnel' is ignored for HTX proxies.\n",
+				   proxy_type_str(curproxy), curproxy->id);
+			curproxy->options &= ~PR_O_HTTP_MODE;
+		}
+
 		/* initialize idle conns lists */
 		for (newsrv = curproxy->srv; newsrv; newsrv = newsrv->next) {
 			int i;
diff --git a/src/mux_h1.c b/src/mux_h1.c
index 2b4e1cf09..9fb570d02 100644
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -616,10 +616,7 @@ static void h1_set_cli_conn_mode(struct h1s *h1s, struct h1m *h1m)
 	struct proxy *fe = h1s->h1c->px;
 	int flag = H1S_F_WANT_KAL; /* For client connection: server-close == keepalive */
 
-	/* Tunnel mode can only by set on the frontend */
-	if ((fe->options & PR_O_HTTP_MODE) == PR_O_HTTP_TUN)
-		flag = H1S_F_WANT_TUN;
-	else if ((fe->options & PR_O_HTTP_MODE) == PR_O_HTTP_CLO)
+	if ((fe->options & PR_O_HTTP_MODE) == PR_O_HTTP_CLO)
 		flag = H1S_F_WANT_CLO;
 
 	/* flags order: CLO > SCL > TUN > KAL */
@@ -668,10 +665,6 @@ static void h1_set_srv_conn_mode(struct h1s *h1s, struct h1m *h1m)
 	int flag =  H1S_F_WANT_KAL;
 	int fe_flags = sess ? sess->fe->options : 0;
 
-	/* Tunnel mode can only by set on the frontend */
-	if ((fe_flags & PR_O_HTTP_MODE) == PR_O_HTTP_TUN)
-		flag = H1S_F_WANT_TUN;
-
 	/* For the server connection: server-close == httpclose */
 	if ((fe_flags & PR_O_HTTP_MODE) == PR_O_HTTP_SCL ||
 	    (be->options & PR_O_HTTP_MODE) == PR_O_HTTP_SCL ||
diff --git a/src/proto_htx.c b/src/proto_htx.c
index e27f24e1b..2ec1dc4d9 100644
--- a/src/proto_htx.c
+++ b/src/proto_htx.c
@@ -2298,12 +2298,8 @@ int htx_response_forward_body(struct stream *s, struct channel *res, int an_bit)
 
 void htx_adjust_conn_mode(struct stream *s, struct http_txn *txn)
 {
-	struct proxy *fe = strm_fe(s);
 	int tmp = TX_CON_WANT_CLO;
 
-	if ((fe->options & PR_O_HTTP_MODE) == PR_O_HTTP_TUN)
-		tmp = TX_CON_WANT_TUN;
-
 	if ((txn->flags & TX_CON_WANT_MSK) < tmp)
 		txn->flags = (txn->flags & ~TX_CON_WANT_MSK) | tmp;
 }