This is not necessarily a corrupt license.db and 40MB could be normal, although that is a bit large. The problem is because of the performance issue that the TR mentioned below is addressing. The issue is that the license tool can’t empty the…
This is a known bug (TR Number: 344799)
Here is the workaround : Rename the license.db and get a copy of it be submitted along with the site id and activation key for the site.