Same problem in Maya but makes sense to add this here. It seems for me the limit is 247 characters, from the beginning of D:\... to the end of .mb
Interestingly, in Windows File Explorer, if you try to rename a file that is less than the limit it won't let you type beyond the limit. However, you can save with a longer file name in Maya, at which point it will also crash Maya, but it will still show the longer file name in File Explorer as if it has saved properly, and then you can make it even longer in File Explorer. BUT you won't be able to open it again in Maya until you reduce the file name below the limit again.
This was causing me such a headache. I was wondering if something in my file was corrupt, or wondering if it was something to do with instanced geometry or the hypershade. I even renamed all the placement nodes and bump nodes and changed Maya switch nodes to aiSwitch nodes incase there was an incompatibility issue. I even exported what I thought was the problem mesh as OBJ and FBX and tried exporting/reimporting. I couldn't work out why I could make instances of the problem mesh in a simple scene and save it and reopen it with no problems, yet the same mesh in my actual scene file wouldn't save after instancing. I also tried Mesh>Cleanup and File>Optimise Scene Size. Sometimes it would crash while saving and sometimes crash when opening. Sometimes it would save and reopen (must have been just on or below the limit) but then when I saved my next iteration with a slightly longer file name it would.... crash!..... making me think it was something to do with the work I had just done. Now I know, it is just the filename length. I must have been unwittingly saving my files just under or just over the character limit, not realising that that was the deciding factor in causing the crashes.
Perhaps other Autodesk programs have the same problem. It would be good if they warn you about file name length at the time of saving. I will submit a request/idea for improvement... but in the Maya forum 🙂
