I've updated AMC to the latest version (4.1.2.3 from 2013-02-10).
When I try to open the database created with the previous version (4.1.1 as far as I remember) I get the following error:
Unable to load file mydatabase.amc. Cannot identify file type by header
This is strange. The header and catalog format have not changed since AMC 4.1.0 so the upgrade should not change anything to your catalog.
Are you sure you open an AMC catalog ?
Does it work with AMC 4.1.1 ?
Good point! I've restores the 4.1.1 beta I had and noticed that actually the database doesn't work there either. Luckily I had a backup, it's a bit old but it won't take long to update it.
Many thanks!