A strange file that creates .bak when categorized [solved]

[michel038]

My settings for metadata:
Export categories to subject xmp and iptc keywords are enabled.

I select the file Ponsonas2.jpg, and mark a category.
- The keywords are updated
- A new file Ponsonas2.jpg.bak is created.

If I move the file to another folder, the problem remains.
If I resize the file and save it as, the problem remains
This file is the only one to have this behaviour

If I download this file from the forum, I can't reproduce the problem
However, I can't see any difference between the original file and the downloaded file

[michel038]

The file was write protected
sorry

I still do not understand how can XnViewMP write keywords in a read only file ...