Forge won't work in the launcher! it says that im using a unsupported modified version of the game! Help!

[fr0gdude]

When i start Forge in my minecraft launcher it goes well at first but then after a while when it starts it just shuts down and says " It looks like you are using an unsupported modified version of the game" and "The game crashed whilst initializing game" and it just won't work. I have checked so that i have uptdate 1.12.2 on forge,minecraft and all the mods (4) i downloaded so i don't know what could be wrong! Here is the error thingy:  Error: java.lang.NoClassDefFoundError: com/mia/craftstudio/IPackReaderCallback

[MDW01]

Remove craft studio if that doesn't fix it post the whole log

[larsgerrits]

Do you have DecoCraft2 installed? And do you have PTRLib installed with it?

[fr0gdude]

i din't know why it says that craftstudio is the problem because i don't even have craftstudio downloaded. And i downloaded decocraft , but not decocraft 2 i think... And what is PTRLib?

[larsgerrits]

4 hours ago, fr0gdude said:

what is PTRLib?

It's a library which is required to be installed for DecoCraft to run. Try installing it, a quick search online revealed the same issue with PTRLib missing.