File history warning

When I click on the file history menu entry on Seahub, then a warning message appears in the seahub.log log:
2020-03-16 19:11:09,560 [WARNING] seahub.views:778 file_revisions Wrong type of suffix_list: None
And for some files, it doesn’t show any history (the rotating icon is constantly moving).
I ran version 7.0.5 CE before and didn’t see this warning. Now, 7.1.2 CE is used. I hope the bug will be fixed when 7.1 will go out of beta status.
How can this be fixed? Is it a consequence of somehow failed update?