Persistent internal error message even after reinstalling

Internal error code: (1033274218:408+516) libgit2 error -1 (14/Failed to insert entry.  Invalid name for a tree entry -.) returned from git_treebuilder_insert(NULL,treebuilderP.get(), (char*)node_nameZ,&oid, mode)

I was going back and forth between Ai and Ch without a problem.  When the error message first showed, I deleted my project and scene.  When that didn't work, I uninstalled Ch and Ae.  But the problem persists.

Any advice on how to go forward from this?

PS:  It seems to be specific to a particular Ai file that I'm trying to import (as once freshly opened, the app allows me to download project files from the forum).  Perhaps I broke something in the source Ai file. I feel like my naming and hierarchy is sound.  I started with a pre-made file from Dave Werner (Okay Samurai), made a huge number of changes, but only had a problem at the end.