Getting "fatal: Authentication failed" -error when sending git commands in Windows 10

The password is stored in windows credential manager and needs to be updated. Open command prompt and enter the following command to view the list of stored passwords:

rundll32.exe keymgr.dll,KRShowKeyMgr

Scroll down in the list until you spot the git-related entries. Click it and edit the correct password.

Voilà!

I agree with Jesper, Other way to do is - On windows, if you can navigate to :

Control Panel\User Accounts\Credential Manager

Under Windows Credentials\Windows Vault page on Generic Credentials, you can update the password of existing GIT record or can also add new Generic Credentials.

Updated answer for Mac users :

In case if you're here with similar issue on Mac, you can do similar thing in keychain access - by deleting the existing GIT record, & then if you pass your credentials again in git bash or any other tool a new record gets created, things should work.

Try the following:

1. Click Start
2. Type: Credential Manager
3. See the Windows Credential Manager shortcut and double-click it to open the application.
4. Once the app is open, click on the "Windows Credentials" tab.
5. Locate the credentials that you want removed, they will start with "git:" and might begin with "ada:"
6. Click on the credential entry, it will open a detail view of the entry.
7. Click Remove and confirm removal when prompted.