Problem:
After installing git credential manager core, you see this error message:
fatal: No credential backing store has been selected. Set the GCM_CREDENTIAL_STORE environment variable or the credential.credentialStore Git configuration setting to one of the following options: secretservice : freedesktop.org Secret Service (requires graphical interface) gpg : GNU `pass` compatible credential storage (requires GPG and `pass`) cache : Git's in-memory credential cache plaintext : store credentials in plain-text files (UNSECURE) See https://aka.ms/gcmcore-linuxcredstores for more information.
Solution:
If you are on a graphical computer, run
git config --global credential.credentialStore secretservice
On a server, if automated i.e. passwordless access is required, use
git config --global credential.credentialStore plaintext
Note that this is insecure since all the passwords are stored in a plaintext file.