I was accessing www.example.com/RestAPI/index.php/tweets.json in my server. The modsec_audit.log showed the following error, but there is no related errors/warnings in modsec_debug.log. I could see the Internal Server error is logged in example-error_log. How can I debug this Internal Server error? --8560e90b-A-- [21/Mar/2012:07:01:52 +0000] T2l84H8AAAEAAGxPZ@QAAAAG x.x.x.x 33101 x.x.x.x 80 --8560e90b-B-- GET /RestAPI/index.php/tweets.json HTTP/1.1 Host: www.example.com User-Agent: Mozilla/5.0 (X11; Linux i686; rv:11.0) Gecko/20100101 Firefox/11.0 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8 Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip, deflate DNT: 1 Cookie: __utma=159129855.1463065063.1331789485.1331789485.1331789485.1; __utmz=159129855.1331789485.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); 8cb6a414cf5ec1919864de0e80bea4da=0es7dcu0p10cocfpferb2lddi0; 8926e4f3c475bb6fcacb409299f1bd27=53cf8c5e6bf78ea45096945377e6d609 Connection: keep-alive Cache-Control: max-age=0 --8560e90b-F-- HTTP/1.0 500 Internal Server Error X-Powered-By: PHP/5.3.5 Content-Length: 0 Connection: close Content-Type: text/html; charset=UTF-8 --8560e90b-H-- Apache-Handler: php5-script Stopwatch: 1332313312358005 130428 (- - -) Producer: ModSecurity for Apache/2.5.12 (http://www.modsecurity.org/); core ruleset/2.0.5. Server: Apache --8560e90b-Z--