Apache Cookbook, 2nd Edition

3.2. Getting More Detailed Errors

Problem

You want more information in the error log in order to debug a problem.

Solution

Change (or add) the LogLevel line in your httpd.conf file. There are several possible arguments, which are enumerated here.

For example:

LogLevel Debug

Discussion

There are several hierarchical levels of error logging available, each identified by its own keyword. The default value of LogLevel is warn. Listed in descending order of importance, the possible values are:

emerg

Emergencies; Web server is unusable

alert

Action must be taken immediately

crit

Critical conditions

error

Error conditions

warn

Warning conditions

notice

Normal but significant condition

info

Informational

debug

Debug-level messages

emerg results in the least information being recorded and debug in the most. However, at debug level a lot of information will probably be recorded that is unrelated to the issue you’re investigating, so it’s a good idea to revert to the previous setting when the problem is solved.

Even though the various logging levels are hierarchical in nature, one oddity is that notice level messages are always logged regardless of the setting of the LogLevel directive.

The severity levels are rather loosely defined and even more loosely applied. In other words, the severity at which a particular error condition gets logged is decided at the discretion of the developer who wrote the code—your opinion may differ.

Here are some sample messages of various severities:

[Thu Apr 18 01:37:40 2002] [alert] [client ...