Why is AJAX returning HTTP status code 0?

Question

For some reason, while using AJAX (with my dashcode developed application) the browser just stops uploading and returns status codes of 0. Why does this happen?

Answer 1

We had similar problem - status code 0 on jquery ajax call - and it took us whole day to diagnose it. Since no one had mentioned this reason yet, I thought I'll share.

In our case the problem was HTTP server crash. Some bug in PHP was blowing Apache, so on client end it looked like this:

mirek@toccata:~$ telnet our.server.com 80
Trying 180.153.xxx.xxx...
Connected to our.server.com.
Escape character is '^]'.
GET /test.php HTTP/1.0
Host: our.server.com

Connection closed by foreign host.
mirek@toccata:~$ 

where test.php contained the crashing code. No data returned from the server (not even headers) => ajax call was aborted with status 0.

Answer 2

I found another case where jquery gives you status code 0 -- if for some reason XMLHttpRequest is not defined, you'll get this error.

Obviously this won't normally happen on the web, but a bug in a nightly firefox build caused this to crop up in an add-on I was writing. :)

Answer 3

Same problem here when using <button onclick="">submit</button>. Then solved by using <input type="button" onclick="">

Answer 4

I had the same problem, and it was related to XSS (cross site scripting) block by the browser. I managed to make it work using a server.

Take a look at: http://www.daniweb.com/web-development/javascript-dhtml-ajax/threads/282972/why-am-i-getting-xmlhttprequest.status0

Answer 5

In my case, it was caused by running my django server under http://127.0.0.1:8000/ but sending the ajax call to http://localhost:8000/. Even though you would expect them to map to the same address, they don't so make sure you're not sending your requests to localhost.

Answer 6

Another case:

It could be possible to get a status code of 0 if you have sent an AJAX call and a refresh of the browser was triggered before getting the AJAX response. The AJAX call will be cancelled and you will get this status.