CRM 2016 - Login to CRM 2016 throw NullReferenceException

Hi all,

When I login to a CRM site, I got "Object reference not set to an instance of an object" and the stack:

[NullReferenceException: Object reference not set to an instance of an object.]

at Microsoft.Crm.Application.SiteMap.GetDefaultUserAreaInternal(IUser user)

at Microsoft.Crm.Application.SiteMap.GetDefaultUserArea(IUser user)

at Microsoft.Crm.Application.SiteMap.GetDefaultUserSubArea(IUser user)

....

I can't access the site anymore to make change or configure

Do you have any idea why I'm getting this error and how do I fix it?

Thanks,

Sam