You might receive this error message while trying to link your Steam ID to your Runic account here.

In almost all cases, this issue is caused when the user has previously linked their Steam ID to a Runic account. Then, at some point later, the user tries to link their Steam ID to a different Runic account, forgetting that the Steam ID may only be linked to one Runic account.

Try checking for various username possibilities under which you might have created a different Runic account. If necessary, perform a password reset for alternative username and email address permutations to recover it. If you experience issues resetting your password, please read Password Reset Issues.

If you are still unable to link your Runic account to Steam, please contact Customer Support and provide the following information:

• Your Steam community profile URL (For example: http://steamcommunity.com/id/RunicCSR)
• Your Runic account name