Chocolate Doom displays this error when i test a level.

[GooCharlie]

what does "W_LumpLength: 2943 >= numlumps" mean? and how can i fix it?

[Edward850]

Are you editing PNAMES and TEXTURE1? If so make sure they still contain the base Doom2 textures and patches. These lumps do not stack and missing references will make the texture entries unloadable.

(For the record, the error explicitly means something in Chocolate Doom is trying to read a lump entry that exists beyond the end of the lump list.)