How to debug Apache mod_rewrite

Question

I have two main problems with mod_rewrite:

1) There is no meaningful error reported when I have an invalid rule

Answer 1

The LogRewrite directive as mentioned by Ben is not available anymore in Apache 2.4. You need to use the LogLevel directive instead. E.g.

LogLevel alert rewrite:trace6

See http://httpd.apache.org/docs/2.4/mod/mod_rewrite.html#logging

Answer 2

There's the htaccess tester.

It shows which conditions were tested for a certain URL, which ones met the criteria and which rules got executed.

It seems to have some glitches, though.

Answer 3

For basic URL resolution, use a command line fetcher like wget or curl to do the testing, rather than a manual browser. Then you don't have to clear any cache; just up arrow and Enter in a shell to re-run your test fetches.

Answer 4

Based on Ben's answer you you could do the following when running apache on Linux (Debian in my case).

First create the file rewrite-log.load

/etc/apache2/mods-availabe/rewrite-log.load

RewriteLog "/var/log/apache2/rewrite.log"
RewriteLogLevel 3

Then enter

$ a2enmod rewrite-log

followed by

$ service apache2 restart

And when you finished with debuging your rewrite rules

$ a2dismod rewrite-log && service apache2 restart

Answer 5

One trick is to turn on the rewrite log. To turn it on,try these lines in your apache main config or current virtual host file (not in .htaccess):

RewriteEngine On
RewriteLog "/var/log/apache2/rewrite.log"
RewriteLogLevel 3

Since Apache httpd 2.4 mod_rewrite RewriteLog and RewriteLogLevel directives has been completely replaced by the new per-module logging configuration.

LogLevel alert rewrite:trace6