This error message may appear in two different situations :
- The file is from an earlier version of the software and has never been opened in the current version.
- The file has already been opened in the current version.
Your file has most likeky been damaged by a third party program running on your computer (most often it might be an anti-virus software program or a cloud backup app ).
This problem can be solved in two steps:
Step 1:
See the article below:
Restore the ".bak" file via Heredis
If step 1 does not solve the problem, proceed to step 2.
Step 2:
See the article below: