> > > [..] and that worked, other than it would ask for credentials every time (instead of caching them). It appears now that only GCM Core is available, however.

[Gahona47]

          > > > [..] and that worked, other than it would ask for credentials every time (instead of caching them). It appears now that only GCM Core is available, however.

This will be the same underlying problem. GCM for Windows will have been prompting you each time because it was failing to persist credentials in the store. GCM (Core) is instead failing up-front because it has detected persistence is broken for some reason.
Please can you try changing the backing store that is being used to one that is more reliable?

git config --global credential.credentialStore dpapi

This will tell GCM to write credentials to encrypted files under %USERPROFILE%\.gcm\dpapi_store rather than use the Windows Credential Manager store (which is seemingly not working for you).

it fixed my issue that it "Unable to persist credentials with the 'wincredman' credential store."

I had this same issue and this resolved my issue as well

Originally posted by @DanWaheed in #633 (comment)