In my case; the public key i was trying to add was already used with ‘work’ Gitlab account and i received the said error upon trying to use the same key with ‘personal’ Gitlab account.
Solution – Add another public key on the same machine and use that with ‘personal’ gitlab account (both on same machine).
navigate to .ssh folder in your profile (even works on windows) and run command
ssh-keygen -t rsa
when asked for file name give another filename id_rsa_2 (or any other).
enter for no passphrase (or otherwise).
You will end up making id_rsa_2 and id_rsa_2.pub
use the command
cat id_rsa_2.pub
copy and save key in ‘personal’ Gitlab account.
create a file with no extension in .ssh folder named ‘config’
put this block of configuration in your config file
Host gitlab.com
HostName gitlab.com
IdentityFile C:\Users\<user name>\.ssh\id_rsa
User <user name>
Host gitlab_2
HostName gitlab.com
IdentityFile C:\Users\<user name>\.ssh\id_rsa_2
User <user name>
now whenever you want to use ‘personal’ gitlab account simply change alias in git URLs for action to remote servers.
for example
instead of using
git clone git@gitlab.com:…………..
simply use
git clone git@gitlab_2:……………
doing that would use the second configuration with gitlab.com (from ‘config’ file) and will use the new id_rsa_2 key pair for authentication.
Find more about above commands on this link
https://clubmate.fi/how-to-setup-and-manage-multiple-ssh-keys/