How do you fix a 502 after changing PHP version in aaPanel?
Check the site's Nginx error log, confirm its selected PHP version, and verify that the matching PHP-FPM service is healthy and listening where Nginx expects it. Restore the last working selection if necessary and application-compatible. A 502 alone does not identify the cause.

Scope and review: Documentation reviewed 9 October 2026. This covers Nginx with panel-managed PHP-FPM after a PHP-version change, not every 502 or an OpenLiteSpeed/Apache deployment. Fresh-VPS reproduction and screenshots are pending. Record aaPanel, OS, Nginx and PHP versions. PHP 8.3 and example.com below are placeholders.

1. Correlate the failure with the site's error log
Confirm the actual log path in aaPanel and reproduce one failing request:

• Permission denied: inspect socket ownership/mode and security-policy denials; do not use chmod 777 or disable security globally.
  
• Connection refused: check whether the configured listener is active.
  
• Upstream timed out: investigate slow application/database work and resource pressure; do not blindly increase timeouts.
  

• The selected PHP service stays running and the expected listener is active.
  
• A real PHP/application route loads, not just a static HTML page.
  
• A new request produces no matching upstream error.
  
• Other sites using that PHP version still work.
  
• Required extensions and application/database operations are checked.
  

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1. Search first. The search box at the top of every page covers all threads, so try your exact error message.
   
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3. Include your panel, OS, web server and PHP versions, and paste logs in [code] tags with passwords and IPs removed.
   

Hi everyone, I'm Jay Dev, the founder of AdminsForum.

A bit about me
I've been building and running websites and the servers behind them since 2013, as a developer and as the person who gets the call when something breaks.

Over the years I've worked with many hosting control panels, both free and commercial, and I don't push any one of them. Each panel has its strengths, and the right choice depends on your server and your sites. Like most admins, I've chased my share of 502 Bad Gateway errors, PHP-FPM problems, broken SSL renewals and mail that suddenly stopped delivering.

Why I started AdminsForum
Help for free hosting control panels is scattered across GitHub issues, old forum threads and machine-translated docs. Too often the answer you need is half-finished, out of date or written for a different version.

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Welcome! Please read this before you post.

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Everyone here was a beginner once. Disagree with ideas, not people. No insults, harassment, hate speech or personal attacks.

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How to ask a good question

• Your panel and its version (aaPanel 7, CyberPanel 2.3, HestiaCP 1.8 and so on)
  
• Your OS and version (Ubuntu 24.04, Debian 12, AlmaLinux 9 and so on)
  
• Your web server and PHP version
  
• What you changed right before the problem started
  
• The exact error message and the relevant log lines, pasted in a code block (the # button in the editor)
  
• What you've already tried