Issue Summary
Our WordPress site experienced a critical issue following a configuration update in the wp-settings file, resulting in a widespread 500 error for most user requests. The incident occurred on November 4, 2023, from 3:44 p.m. to 4:30 p.m. EAT. During the peak of the incident, nearly all user requests resulted in 500 errors. The root cause was identified as a grammatical error in the latest update of the settings file, where a file inclusion had the incorrect “.phpp” extension instead of “.php”.

Timeline
Timezone: East African Time (EAT)

Outage Duration: 3:44 pm to 4:30 pm

Start time: 3:44 p.m.

Staff Notification: 3:50 pm

Actions
3:50 pm to 4:15 pm: Investigation using tmux, strace, and curl

4:15 pm: Identification of the grammatical error in wp-settings

4:30 pm: Site restoration online.

Root Cause
The incident was caused by a grammatical error in the wp-settings file. Specifically, a recent update introduced a file inclusion with the incorrect extension “.phpp” instead of the required “.php”. This error resulted in a cascade of 500 errors for user requests, rendering the site inaccessible.

Resolution and Recovery
To address the issue, a puppet manifest was created. The manifest targeted the wp-settings file, identified the incorrect “.phpp” extension, and replaced it with the correct “.php”. The corrective action took place between 4:15 p.m. and 4:30 p.m., restoring the site’s functionality.

Corrective and preventative measures
Code Review Procedures
Implement stringent code review processes to catch grammatical errors and typos in configuration files before updates are deployed.

Automated Testing
Introduce automated testing for configuration files to identify potential errors and inconsistencies prior to deployment.

Monitoring and Alerts:
Enhance monitoring systems to provide immediate alerts for 500 errors or similar critical issues, ensuring swift response times.

Documentation Updates
Maintain up-to-date documentation outlining file inclusion standards and syntax to avoid similar grammatical errors in the future.

Training and Awareness
Conduct training sessions to raise the team's awareness of the importance of meticulous code reviews and the potential impact of configuration errors.

Lessons Learned
The incident underscores the significance of thorough code reviews, automated testing, and vigilant monitoring to prevent and quickly address configuration errors that can lead to service outages. Regular training and documentation updates are crucial to maintaining a proactive approach to system stability.

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