i've installed BFX, Dev's side mod and the map named zzz so that the computer take the hero.
this all works fine. then i renamed the addme file from zzz and dev's side mod so i could test other mods and maps without getting the 500 mission error.

now i've installed BFX, Dev's side mod, the map named zzz so that the computer take the hero, The Dark times and Battlefront Projekt. all workes fine. then i named the addme file from zzz and dev's side mod addme.script so i can play them again.
there was no 500 mission error, but Dev's side mod does only work on the maps from the mod and not on the original SWBFII maps. there isn't Dev's side mod there are the icon from Yuuzhan Vong (i don't know if this exist) and an other i don't remember yet. i tried to play this but the game crashes.

Also the icon from The dark times and the name are not correct on the Original SWBFII maps.

Instead of renaming you should simply move the folders out of "addon". Create a folder like "addon disabled" and try starting the game with only some mods active.

i did. there wasn't the problem before and rename and remove is the same on other mods maps i did it always no problme

Have you tried to reinstall?

what the mod or the game or both??

If you want, reinstall the mod first. I don't think it is neccesary to reinstall the game too.