I am using SBCL 1.04. I've just upgraded to latest hunchentoot, drakma etc...
It happens when I upload a file using POST request. Most of the times the http-request just works and returns the result which I parse and it's meaningful. Occasionally (1 out of 10 times) the http-request returns nil. To verify it, I tested it not from the web, but from the slime propt. It it took me a while to understand why my web app was misbehaving sometimes.
For now I put a workaround like
(loop for i from 0 to 5 while (not http-request-result) do
        (setq http-request-result (drakma:http-request ....))
which works.
I'd like to know if it's an expected behavior of the http request or is there something I/we could do to fix it?

Thank you,
Andrew