Error message when opening a server-based termbase in GroupShare: "The transaction log for database 'MTMaster_XX' is full"

When trying to open a server-based termbase from MultiTerm Server component of Trados GroupShare, you get the following error message:
Similar symptoms are that the server-based termbase can be opened. However, when trying to add or edit a term the same error message is displayed:

Review Transaction Log size and/or disk space...

NOTE: The Transaction Log is not managed by SDL applications but rather by the Microsoft SQL Server. To resolve this problem, contact your local/external (IT-) Database Administrator to handle/decide how and where to increase the limit or free up disk space.

This error occurs when the SQL Database Transaction Log reaches the limit of space available and therefore cannot ‘write’ data to the database anymore. Ask your database administrator to increase the limit or free up more space on the SQL Server.
If you are using SQL Server Express, this version is limited as to the size of databases.