Plesk is showing error 502 after enabling SQL debug: PHP Fatal error: Couldn't execute method Zend_Log::__destruct in Unknown on line 0

Gabriel Aznarez

Updated January 13, 2026 19:08

kb: technical

Symptoms

Plesk version is 18.0.50 and debug log with option show.sql_query = on is activated.
Plesk panel is showing error 502:

CONFIG_TEXT: PHP Fatal error: Couldn't execute method Zend_Log::__destruct in Unknown on line 0
Errors like the following example can be found at /var/log/sw-cp-server/error_log:

CONFIG_TEXT: [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"

Product issue:

#PPPM-13885 "Enabling debug logging in Plesk no longer makes the Plesk GUI inaccessible with the âHTTP 502 Bad Gatewayâ error."
Fixed in:
- Plesk Obsidian 18.0.51 14 March 2023 (Linux)
- Plesk Obsidian 18.0.50 Update 1 08 February 2023 (Linux)

Please consider updating your server:

If update is not possible for some reason you may try the following

workaround

Until the fix becomes available as workaround:

Edit Plesk panel.ini file to add the following line under the [log] section:

CONFIG_TEXT: [log]
firebug = 1

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