What is error 500?

Error 500 Internal Server Error is a generic HTTP status code indicating a problem on the server side that is not specific and cannot be more clearly identified.

Essentially, it means that the server encountered an unexpected condition that prevented it from fulfilling the request from the sender.

Possible causes:

• Server-side code errors: Incorrectly written code, unhandled exceptions.
• Database issues: Connection errors, incorrect queries, overload.
• Server configuration errors: Incorrect web server settings (Apache, Nginx), issues with .htaccess files, permissions.
• External service issues: If the server calls another service, and it is unavailable or returns an error.
• Insufficient server resources: CPU overload, lack of memory or disk space.
• Third-party plugin or module errors: In case of CMS or frameworks.

From a QA perspective, upon discovering a 500 error, it is necessary to:

1. Check server logs (access to them is crucial).
2. Find out the context of the error occurrence (which request was made, which user, what data was sent).
3. Try to reproduce the error.
4. Report the problem to the development team, providing detailed reproduction steps and log data.

Example of a log entry that may indicate a 500 error (depends on server configuration):

[Mon Sep 04 10:00:00.000000 2023] [php:error] [pid 1234] [client 192.168.1.100:45678] PHP Fatal error:  Uncaught Exception: Database connection failed in /var/www/html/index.php:10 Stack trace: #0 {main}   thrown in /var/www/html/index.php on line 10