Making an intermittent fault testable.
WHY IT MATTERS
You cannot confirm a fix for something you cannot trigger.
WHAT TO ESTABLISH
Does it happen every time, or sometimes Does it happen for everyone, or only some visitors Does it happen on all pages or specific ones Does it happen on all devices and browsers Does it happen when logged in, logged out, or both
THE COMMON PATTERNS
- Only when logged out: caching, since logged-in users bypass cache
- Only on mobile: a responsive or device-specific issue
- Only at busy times: resource limits
- Only on one page: something specific to that page
- Only for you: a local problem, a cached version, or a firewall block
TESTING PROPERLY
Use a private browsing window, which eliminates cached content and session state.
Test on a different device and a different network.
FOR INTERMITTENT FAULTS
Note the exact times. Correlate against resource usage graphs and against cron schedules.
A fault occurring hourly at the same minute is a scheduled task.
WHAT TO RECORD
Time, page, device, browser, logged in or out, and what you were doing.
