Apache
Apache HTTP Server errors, module problems and .htaccess mistakes.
- Apache error log: where it is, how to read it and common entriesThe Apache error log is the first place to look when httpd won't start or returns 403, 404 or 500 with no obvious reason. Find its path with the `ErrorLog` directive, watch it with `tail -f` while you reproduce the problem, and search by the `AHnnnnn` code in each entry. If the log looks empty, the usual reasons are a `LogLevel` that hides the message, a per-virtual-host log, or a log that was not reopened after rotation.
- Apache 500 Internal Server Error: how to find the cause and fix itA 500 from Apache is a generic "something went wrong" status, so the error page itself does not tell you the cause. The reason is written in the Apache error log. Read it first, then check the file or directive it names, such as a `.htaccess` file or a failing script.