What Is an Error Log?
An error log is a file where a web server records information about errors that occur during request processing. This includes PHP fatal errors, permission denied messages, missing files, timeout errors, and configuration problems. Unlike access logs that record every request, error logs only capture events when something goes wrong.
Why Error Logs Matter
Error logs are critical for diagnosing server-side issues that affect SEO. A sudden spike in 500 errors visible in your error log means search engines are receiving server errors when trying to crawl your pages — directly harming your indexation. Error logs also reveal misconfigurations, resource exhaustion, and application crashes that access logs alone cannot explain.
How to Use Error Logs
Error logs are typically found at /var/log/nginx/error.log or /var/log/apache2/error.log. Monitor them regularly for recurring patterns: repeated file-not-found errors may indicate broken internal links, while memory exhaustion errors suggest you need to optimize your application. Tools like LogBeast can correlate error log entries with access log requests to give you the full picture.
📖 Related Article: Server Log Analysis for SEO — Read our in-depth guide for practical examples and advanced techniques.
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