Pregenerated my world offline only to not be able to join it now

Allright, so, i tried playing on a fabric modded server, ran into issue of really slow chunk loading so i decided to pregen some odd 50k chunks using "Fabric Chunk Pregenerator".

Now i cannot login into the server with an error message: Internal Exception: io.netty.handler.codec.DecoderException:java.lang.IndexOutOfBoundsException: readerInderx(31) + lenght(1) exceeds writerIndex(31): PooledUnsafeDirectByteBuf(ridx:31m widx:31. cap:31/32).

After i got this error i loaded a backup and i could join back in, so my assumption was that the pregen probably loaded too many chunks for the server to turn on now, so should i pregen less, or should i just not bother doing so at all?

I am using the Medeival Mc fabric V5 modpack, only thing i added was the world pregen, so that addition could also be what is not letting me turn join the server now. Altough i have no idea.

EDIT: Managed to log onto the server right as it loaded, but once i logged out and tried to get back it would not work showing the same error message

Uhm, halo? Not even a "we dont know"????? Okay lmfao

Thx for the help, but now i got another issue. The modpack did not update. I did not change anything on the server, BUT now i cant login because the server says the versions are incopatible. Did the version of medieval mc on here change over night? Or what did even happen?

Figured out what the issue was. But now i got a problem with the fact ive spent a while on a world and i would like to continue with it, BUT i doubt it will work well with the new version of the modpack since it has about 60 less mods.

Is it possible to change the modpack version on here, or should i just forget about the world and start a new one?

Yeah, but i played a ton on the previous version and i doubt the world will be compatible with the current one.

But well if its not possible to change modpack versions i will just play a new world. Its w/e i guess

The change log did mention they do not reccomend using the same world on the new version. So its just a matter of a new world. Hopefully they wont make any massive changes for a while