ErrorCode=9250 when attempting to log into Business Manager for B2C Commerce

The user is able to log into Account Manager but experiences a "An error has occurred. Please contact the administrator. [ErrorCode=9250]" error when attempting to log into Business Manager. 

This error typically occurs when the user profile exists and is linked in Business Manager, but the Account Manager profile was purged and re-created (using the same email address). This happens because the UUID of the user in Account Manager now differs from the UUID in Business Manager.