Too many "Background process error"s from a failed chmod

[aleksejrs]

If I try to chmod files that cannot be chmod'ed, I get a separate "Background Process Error. chmod: changing permissions of '…': Operation not permitted` popup for each file, which apparently cannot be stopped.
Vifm 0.13

The current directory belonged to thisuser:commongroup and was drwxrws--- (770), but the files in it belonged to a different user and a different group, and I tried to :chmod o-rwx the files.