[korben]

@BetterRed : changing Environment variable for CALIBRE_TEMP_DIR doesn't match because I think Editor's temp dir must be different.
I've done it to test eventually with the calibre's temp dir but no result (I've verified the change was effective with the "printenv" command).
In fact, if I could know the name of the variable of the editor's temp dir, I'm sure this will work.

@kovidgoyal : thanks for your intervention.

I'm not sure it is a temp dir problem cause I can open and modify the books. It's only when saving that the problem is.

K