Tomcat – Apache + Tomcat giving error 500 for non-browser agents (Struts2)

500apache-2.2tomcat

I've got an Apache WebServer + Tomcat 7 serving Struts2 web pages. It works without problems when I use any web browser, but when I try to access a web page using W3C validator or Facebook Lint, the server returns the error 500.

[28/Oct/2011:21:45:58 +0100] "GET /agenda7/event?id=124 HTTP/1.1" 200 9898 
"-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_2) 
AppleWebKit/534.51.22 (KHTML, like Gecko) Version/5.1.1 Safari/534.51.22"

[28/Oct/2011:21:47:16 +0100] "GET /agenda7/event?id=124 HTTP/1.0" 500 6287 "-" 
"facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)"

[28/Oct/2011:21:47:42 +0100] "GET /agenda7/event?id=124 HTTP/1.1" 500 6287 "-" 
"W3C_Validator/1.2"

Somehow, it fells like those services cannot understand how to make the get request to a web page without extension, but, if that were the case, shouldn't the error be 404?

Any suggestions?

EDIT:

Just tested this with an alternative mapping, and the problem persists:

[28/Oct/2011:22:54:53 +0100] "GET /agenda7/event_124 HTTP/1.0" 500 6364 "-" 
"facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)"

But it works with the index page, for example-:

[28/Oct/2011:22:59:01 +0100] "GET /agenda7/ HTTP/1.0" 200 20666 "-"
"facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)"

Best Answer

A 500 status code means that the code running within Tomcat errored; you should find a stack trace in the logs.

Keep in mind that the requests from those non-browsers are going to be different in subtle ways; the Facebook hit is HTTP/1.0, for example.

It's likely that your code is looking for something in request headers or cookies that is there with the browser request and not there in the bot requests.

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