After updating Git to 2.19.1 this morning, I wasn't able to push or pull from our internal Bitbucket company repository.

git -c diff.mnemonicprefix=false -c core.quotepath=false --no-optional-locks push -v --tags origin master:master
 fatal: ArgumentException encountered.
 An element with the same key has alredy been added
fatal: ArgumentException encountered.
fatal: Authentication failed for 'https://<user>@<my-bitbucket-url>'
 Pushing to https://<user>@<my-bitbucket-url>

I searched in the GUI for stored credentials. neither in SourceTree, nor in the Windows credential store were any found. Using CLI from git it works.

Found %localappdata%\Atlassian\SourceTree\passwd and noticed that my Bitbucket password is present in it, altough the GUI in options say that no stored credential exists:

After deleting those passwd file, SourceTree ask me for credentials and pushing/polling is possible. When checking the "save credentials" checkbox, the file is re-created. But in the GUI I still can't see the credentials.