CentOS Stream 10 – Common Problem 249 – Diagnosis and Fix

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

nginx returns 502 Bad Gateway because it cannot write to the PHP-FPM Unix socket.

Environment & Reproduction

Triggered when listen.owner and listen.group in www.conf do not match the nginx runtime user.

Root Cause Analysis

SELinux or POSIX permissions prevent nginx from connecting to the FPM socket file.

Quick Triage

Inspect /var/log/nginx/error.log and ls -l on the configured socket path.

Step-by-Step Diagnosis

Run: sudo ls -l /run/php-fpm/www.sock; sudo journalctl -u php-fpm; getenforce.

Solution – Primary Fix

Set listen.owner = nginx and listen.group = nginx in /etc/php-fpm.d/www.conf and reload php-fpm.

Solution – Alternative Approaches

Switch to TCP socket on 127.0.0.1:9000 if SELinux complicates Unix socket sharing.

Verification & Acceptance Criteria

nginx serves PHP pages without 502 errors and curl -I returns 200 from a test PHP script.

Rollback Plan

Revert www.conf to apache:apache ownership and restart php-fpm if nginx is removed.

Prevention & Hardening

Document expected listen.owner/group per stack and check after every php-fpm upgrade.

Related Errors & Cross-Refs

Related to SELinux httpd_can_network_connect booleans and ACL inheritance issues.

Related tutorial: View the step-by-step tutorial for centos-stream-10.

View all centos-stream-10 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

php-fpm.conf(5) and Red Hat web application guide.