502 Error¶
In some cases, instead of the admin interface, a white page with “502 Error” is displayed
In this case, you need to open the server console and check the following:
- The DBMS is running. 
sudo service postgresql status
if the service is not running, you should restart it
sudo service postgresql restart
- If it still doesn’t help, then most likely we have a problem with the database. The problems may vary, but the most likely one is the disk overload. 
df -h
If we see that the disk is 100% filled, then we need to perform automatic or manual disk cleaning.
- Restart staffcop service 
sudo service staffcop restart