Hello Patricia Burke ,

The error message implies that the TB has become corrupted (irelevant of the version).

Please take a look at the following article to perform the necessary fix

https://gateway.sdl.com/apex/communityknowledge?articleName=000002800

Hallo Steven,

Thank you for your reply. I do not have a licence for Access and have applied for one from our IT department. In the end I had to rebuild from scratch to resolve this issue which cost me a lot of time.
On the whole I have to say I am very disappointed with the stability issues of 2019.
Regards
Patricia Burke
 

I have had the same problem today after importing one entry from another termbase using "fast import". I use Trados Studio 2019 and Multiterm 2019. Fortunately, I had made a copy of the termbase last week and could open it. 

I imported the same entry in a test environment, but this time I did not use "Fast import" and checked "Perform full reorganisation after import".  Everything went smoothly and the termbase is working.

SDL should fix this issue.