Microsoft Dynamics CRM on-premise - The system could not log you on - error for all users solved

I was working on a support case for a client, they said that no user can login to the system, and the system gives them an error message "The system could not log you on. This could be because your user record or the business unit you belong to has been disabled in Microsoft Dynamics CRM" and there is no user I can login with to enable other users.

What causes this?

Well, they thought that no one is using the admin user, why to consume a license for this one, they disabled the admin user, then login attempts failed because of that.

Recommendation?

Just DON'T disable the admin user.

Solution:

This is the solution I found, if you have a better one please provide it to us!

1. Take a backup of the CRM database

2. Write a query for the CRM database

     Update SystemUserBase SET IsDisabled='false' WHERE (DomainName = ‘AdminUsername')

Then execute the query, the admin user then can login so the other enabled users.

Note: make sure to retrieve users and check the username before executing this query.

Note: the username usually will be as "Domain/Username"

Hope this helps.!

Thanks