Access denied for your LDAP account (from Standard to LDAP)

We have an existing user that was created before the ldap sign-in was enforced. Now, we try to ask the user to log in using his ldap credentials but he receives “Access denied for your LDAP account”.

This might be because the same email address was used on the standard account that was created beforehand.

Is there a way for his current standard user to be converted as ldap user? I read some similar issues wherein they change the email address of the current one and have them log in on ldap . But we don’t want to loose his projects on his current user as it is already around 2K projects.

I hope someone can help. Thank you.

This post might help: [Solved] Help! LDAP Migration w/ New Usernames