When attempting to export, blockbench throws out this error and fails to export.

I'm still having this issue, but deleting all existing project files does not seem to resolve the issue.

Update: I've found that deleting the imported skin.png file seems to resolve the issue.

Can you post your model file (.bbmodel) and the texture you are using?

I had this error and I solved it by deleting the old ".cpmproject" file I had.
I guess it crashes whenever you try to export 2 ".cpmproject" files with the same name in the same directory.