The manager does not start.

This answer was fist posted in the FAQ on the modding Discord here.

The easiest and quickest way to solve it is this:

1. Find your mod storage folder (by default it’s C:\Users\<USERNAME>\AppData\Local\Helldivers2ModManager)
2. Go into the mods folder
3. Delete or move mods out of that folder one at a time and check if the manager is working again
4. Reinstall/move back the working mods
5. Mod Manager should be working good now

Video tutorial