After the big update of January 2018 there was reported some issues about the addon not loading. That was because of supposedly outdated dedicated server versions.

Their version numbers were like 8+ month outdated, but that wasn't right as the users could still connect to it with their up to date clients and everything else about the server was right as well. Issues like that are still reported as in today sometimes.

Now I know that it was caused by a game file not being updated on server updates sometimes making them and the offical way of getting the game/server version an unreliable source to check the system to be up to date. The addon however needs it this way.

The affected file is: <server>/garrysmod/garrysmod.ver

You need to repair the affected file through a full validating server update.
Do not edit the file!

1. Stop the dedicated server (very important for the fix)
   
2. Delete "<server>/garrysmod/garrysmod.ver"
   
3. Start steamcmd and login as anonymous
   
4. Run this: app_update 4020 -beta public
   
5. Then run this: app_update 4020 -beta public validate
   
6. Check "<server>/garrysmod/garrysmod.ver" to be at least version 241209 (latest server version)
   
7. Restart the dedicated server, everything should be fine.

Replace "-beta public" with "-beta x86-64" or any other branch you like to use.
Use "-beta public" to force it to use the default (live) version.

• This addon is only supported on the latest official versions of the client and server
  
• On branch versions beside 'live', 'dev' or 'prerelease' this addon works aswell most of the time, but it is not actively supported. Especially on beta or development branches the addon can break temporarily.

1. What do I do, if I don't have access to the server?

• Ask the owners/admins of that server to perform these steps. Show them this guide!

2. What do I do, if the server is run via a third party service, such as a hoster?

1. Stop the dedicated server (very important for the fix)
   
2. Delete "<server>/garrysmod/garrysmod.ver" via file access.
   
3. Run a file validation on that server via the third party service, preferably on the live branch. You can also use your preferred branch if the branch is up to date.
   
4. Restart the dedicated server, everything should be fine.

3. What do I do, I don't have access to the files or to the file validation to the third party service?

• Contact the service's support if necessary. Show them this guide!

4. I don't know how to do (common/general) server administration tasks, can you help me?

• Ask someone who does. Show this guide.
  
• I am not available for server support. Support for server administration is not a part of this addon.
  
• Learn it to do it yourself, it's worth it.

5. Can you fix/change the version checking in the addon?

• No, because it's not broken.
  
• I do not implement server or user specific customisations. I do not support custom versions of anything.

6. But I don't like to restart the dedicated server.

• This is Garry's Mod, not a ~high availability~ system for critical infrastructure. So just do it.

If the addon is still not loading on connection AFTER doing the stuff above. Then report it with ALL error messages to me, please.