Confused about a 404 error on test results

[pmeenan]

OK. That was painful and looks like you may have exposed a bug that WebPagetest isn't catching :-)

protip: If you use Chrome as a test browser then you will get information on what triggered each request to load. Capturing response bodies and a timeline also help.

http://www.webpagetest.org/result/140206...#request76 - shows Initiated By: http://thekitchenshelf.co.uk/ line 545

Looking at the page source: http://www.webpagetest.org/response_body...&request=1 it looks like that's a "add to wishlist button" with a few classes attached as well as the start of an inline script tag.

Unfortunately that was a bit of a dead-end but it does tell us around what element the request is being triggered.

My guess is that there is some js code that lazy-loads or does something with images that isn't dealing with error handling.

You can fetch all of the bodies as a zip file if you tweak the screenshot path and change it to bodies.zip: http://www.webpagetest.org/results/14/02...bodies.zip

Next step is to just grep through all of the bodies looking for not_found. It wasn't in any of the captured response bodies. Time to step up the game and capture a full tcpdump.

Eureka! Searching the raw packets it looks like the request for:

http://thekitchenshelf.co.uk/wp-admin/im..._light.gif

returned a redirect to not_found:

HTTP/1.1 302 Found
Location: http://thekitchenshelf.co.uk/not_found

Now off to figure out why WebPagetest didn't capture the redirect request/response....