As per here:
Can't upload file attachments to phpBB3 forum on IIS
I'm having a problem with the plupload implementation in phpBB3.
I find that I get through
phpbb.plupload.uploader.bind('FilesAdded', function(up, files)
but never get to
phpbb.plupload.uploader.bind('FileUploaded', function(up, file, response)
unless my file is very small (< 5 KB). Is this simply down to reponses from the server (or lack thereof)? Any tips on figuring out the actual problem? So I can stop trying out a bunch of random crap?
EDIT: Fiddler shows that the upload simply doesn't get any response from my server. Using the un-minified plupload files I can see that (I think) everything for the XMLHttpRequest is properly constructed. I essentially get through uploadChunk to xhr.send, but never get to xhr.onload.
How do I debug the server side problem?
It turns out this was a problem with a generic reverse proxy rule on our firewall. Adding a rule to specifically transfer HTTP(s) traffic directly to our webserver (rather than through the reverse proxy table) fixed things.