diff --git a/app/slashcommands/command_channel_header.go b/app/slashcommands/command_channel_header.go
index b2fa143e3b..ab09aab950 100644
--- a/app/slashcommands/command_channel_header.go
+++ b/app/slashcommands/command_channel_header.go
@@ -94,8 +94,15 @@ func (*HeaderProvider) DoCommand(a *app.App, args *model.CommandArgs, message st
 
 	_, err = a.PatchChannel(channel, patch, args.UserId)
 	if err != nil {
+		text := args.T("api.command_channel_header.update_channel.app_error")
+		if err.Id == "model.channel.is_valid.header.app_error" {
+			text = args.T("api.command_channel_header.update_channel.max_length", map[string]interface{}{
+				"MaxLength": model.CHANNEL_HEADER_MAX_RUNES,
+			})
+		}
+
 		return &model.CommandResponse{
-			Text:         args.T("api.command_channel_header.update_channel.app_error"),
+			Text:         text,
 			ResponseType: model.COMMAND_RESPONSE_TYPE_EPHEMERAL,
 		}
 	}
diff --git a/app/slashcommands/command_channel_purpose.go b/app/slashcommands/command_channel_purpose.go
index 668fa001fa..1d350b8499 100644
--- a/app/slashcommands/command_channel_purpose.go
+++ b/app/slashcommands/command_channel_purpose.go
@@ -79,8 +79,15 @@ func (*PurposeProvider) DoCommand(a *app.App, args *model.CommandArgs, message s
 
 	_, err = a.PatchChannel(channel, patch, args.UserId)
 	if err != nil {
+		text := args.T("api.command_channel_purpose.update_channel.app_error")
+		if err.Id == "model.channel.is_valid.purpose.app_error" {
+			text = args.T("api.command_channel_purpose.update_channel.max_length", map[string]interface{}{
+				"MaxLength": model.CHANNEL_PURPOSE_MAX_RUNES,
+			})
+		}
+
 		return &model.CommandResponse{
-			Text:         args.T("api.command_channel_purpose.update_channel.app_error"),
+			Text:         text,
 			ResponseType: model.COMMAND_RESPONSE_TYPE_EPHEMERAL,
 		}
 	}
diff --git a/i18n/en.json b/i18n/en.json
index ff9f4aff91..cae1af740a 100644
--- a/i18n/en.json
+++ b/i18n/en.json
@@ -629,7 +629,11 @@
   },
   {
     "id": "api.command_channel_header.update_channel.app_error",
-    "translation": "Error to update the current channel."
+    "translation": "Error updating the channel header."
+  },
+  {
+    "id": "api.command_channel_header.update_channel.max_length",
+    "translation": "The text entered exceeds the character limit. The channel header is limited to {{.MaxLength}} characters."
   },
   {
     "id": "api.command_channel_purpose.channel.app_error",
@@ -661,7 +665,11 @@
   },
   {
     "id": "api.command_channel_purpose.update_channel.app_error",
-    "translation": "Error to update the current channel."
+    "translation": "Error updating the channel purpose."
+  },
+  {
+    "id": "api.command_channel_purpose.update_channel.max_length",
+    "translation": "The text entered exceeds the character limit. The channel purpose is limited to {{.MaxLength}} characters."
   },
   {
     "id": "api.command_channel_remove.channel.app_error",