SmartGit Hg "Authentication Failed"

This works for me. Go to Edit>Preferences>Hosting Providers. On your Hosting Providers(I use Bitbucket for example) select it, click delete and click add. Select hosting, click Generate API Token automatically opens browser and generates token then copy go back to your smartgit then paste the token and finally click add

Perhaps SmartGit remembers wrong account credentials to authenticate you on BitBucket. Goto Edit menu -> Preferences -> Authentication and remove credentials for the repository that fails. Then next time you push SmartGit will ask you for both login and password.

None of the answers given ended up resolving my issue on SmartGit.

I went in Edit ->Preferences -> Authentication but the list of known credentials was empty so was the list of Hosting Providers.

The reason was that SmartGit was storing my credential in Windows Credential Manager.

To resolve the issue, I went to Control Panel -> Credential Manager -> windows Credentials, select the specific credential you wish to update and choose to edit it and then update your credentials