I recently came across a funny bug where I was executing an AJAX method and the response was empty.
I check the server side and I know that my particular query is returning a result, but thanks to Firebug I can see it's failing in the browser.
So there was something definitely amiss.
In particular, I was returning my result as a JSON object which should have looked like this:
{message: "Order Filled"}
However, Firebug was throwing the following error (within the jQuery library - but I had the same problem when I hadn't used a library):
syntax error data =
The problem is down to the size of the response. It's something like apache is compressing it to nothing. Not very technical I realise - but the solution is to pad the response.
I fixed it by placing a '\n' before the JSON - since it's legal syntax it doesn't cause a problem, and it means the response is read in the browser.
All was well again in the land of AJAX & Remy.