On the night of October 19, we have set up blocking traffic whose user agent is empty, as this is most spam traffic, hacking attempts, etc ....
https://fr.wikipedia.org/wiki/User-Agent

This can cause some problems at some scripts modules that do not have too much attention to the standards or are a bit old.

Either you change the code much easier OR, you must change the profile to avoid this Nginx protection :

http : Custom med proxy to http
https : Custom med proxy to https

https://support.yoorshop.hosting/knowledgebase/2549/How-to-update-Nginx-profile.html 


UPDATE 26 october 2016

This filter has caused various problems to some users, we reduce its perimeter, then no more need to change nginx profile

User agent