Running devmap I get - Server script compile error unknown function (see console for details).

After putting developer 1 in the console I get - unknown function level.achievement_notify_func = maps\_zombiemode_utility::achievement_notify;

What's causing this error?

I had a previous error before where I was missing  _zombiemode_zone_manager.gsc. I came across a post on another website that told someone else to take that file and put it into the mod folder and into maps. After doing that, this new error shows up.

If you are creating a new map from script placer you are likely to hit a few of those errors usually about the missing files ( dlc3 , spawner , zombiemodedogs , dlc3teleporter and so on. The best thing to do is what you already are doing and check your developer 1 for the exact cause of the problem.

It will show you what file and what line the problem is. You can press CTRL+G to search for line number . Then i would recommend posting either a screenshot or copy the error more specifically , as it is difficult to determine your error based on your explanation

Remember to make regularr back ups of your map /mod folder.