Mod_Rewrite enables you to do fancy stuff with URLs, but it isn’t always transparent when it comes to debugging. In a development environment it can be useful to enable apache error logging to see where a mod_rewrite line fails.
In XAMPP you can do this by opening httpd.conf (open control panel > config > Apache (httpd.conf)) and append mod_rewrite.c:trace3 to LogLevel.
LogLevel warn mod_rewrite.c:trace3