Plesk version is 18.0.50 and debug log with option
show.sql_query = onis activated.
Plesk panel is showing error 502:
PHP Fatal error: Couldn't execute method Zend_Log::__destruct in Unknown on line 0
Errors like the following example can be found at
[error] 22640#0: *747 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 127.0.0.1, server: , request: "GET / HTTP/1.0", upstream: "fastcgi://unix:/var/run/sw-engine.sock:", host: "ip address of the host"
If update is not possible for some reason you may try the following
Until the fix becomes available as workaround:
Edit Plesk panel.ini file to add the following line under the
firebug = 1