diff --git a/custom/conf/app.ini.sample b/custom/conf/app.ini.sample
index ca5b7a333..f9a188c3a 100644
--- a/custom/conf/app.ini.sample
+++ b/custom/conf/app.ini.sample
@@ -124,6 +124,7 @@ UNIX_SOCKET_PERMISSION = 666
 ; Local (DMZ) URL for Gitea workers (such as SSH update) accessing web service.
 ; In most cases you do not need to change the default value.
 ; Alter it only if your SSH server node is not the same as HTTP node.
+; Do not set this variable if PROTOCOL is set to 'unix'.
 LOCAL_ROOT_URL = %(PROTOCOL)s://%(HTTP_ADDR)s:%(HTTP_PORT)s/
 ; Disable SSH feature when not available
 DISABLE_SSH = false
diff --git a/docs/content/doc/advanced/config-cheat-sheet.en-us.md b/docs/content/doc/advanced/config-cheat-sheet.en-us.md
index 16d0a50fa..0d2af6237 100644
--- a/docs/content/doc/advanced/config-cheat-sheet.en-us.md
+++ b/docs/content/doc/advanced/config-cheat-sheet.en-us.md
@@ -95,6 +95,11 @@ Values containing `#` or `;` must be quoted using `` ` `` or `"""`.
    - If `PROTOCOL` is set to `fcgi`, Gitea will listen for FastCGI requests on TCP socket
      defined by `HTTP_ADDR` and `HTTP_PORT` configuration settings.
 - `UNIX_SOCKET_PERMISSION`: **666**: Permissions for the Unix socket.
+- `LOCAL_ROOT_URL`: **%(PROTOCOL)s://%(HTTP_ADDR)s:%(HTTP_PORT)s/**: Local
+   (DMZ) URL for Gitea workers (such as SSH update) accessing web service. In
+   most cases you do not need to change the default value. Alter it only if
+   your SSH server node is not the same as HTTP node. Do not set this variable
+   if `PROTOCOL` is set to `unix`.
 - `DISABLE_SSH`: **false**: Disable SSH feature when it's not available.
 - `START_SSH_SERVER`: **false**: When enabled, use the built-in SSH server.
 - `SSH_DOMAIN`: **%(DOMAIN)s**: Domain name of this server, used for displayed clone URL.