Well, that's 'special'! :\ Haven't seen that one before, but then again ...
Thanks for the pic. Did you recently upgrade to 3.2?
(check your Moodle version).
If you recently upgraded, how did that go?
And, one more question ... I can see in the pic you are
attempting restore from the last item in the resources (file systems)
list, I think.
Is that resource remote? or is it local ... i.e., on the same physical
server as the moodle?
In googling for such an error, one will get several hits but none are
specific to Moodle but other apps. Most discussions talk about data (in your case a file) that's being transported. (networking does come before application ... if there is a hickup in network, app is affected).
Can you move the backup to another location/resource Moodle can see (locally - not remote) and try it again?
'spirit of sharing', Ken