Cygwin 3.1.X Fatal Errors - add_item ("\??\C:", "/", ...) failed, errno 22

Ken Turner
Tue Jan 14 11:09:00 GMT 2020

Thanks to Marco for the advice, and special thanks to Henri for additional support.

As noted on, my problem was due to installing Cygwin in the drive root. I was forced to do this some years ago because of a third-party package that required Cygwin to be installed there.

Following a suggestion from Henri, I moved C:\bin, etc. to C:\Cygwin and then ran setup with the latter as the installation directory. I could then apply the 3.1.X update without problems.

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