I've been using the uploadify jquery for a long time - this tool has been working on several different servers for quite a while. Recently, on rackspace cloud sites accounts, the uploads stopped working.

There's been no change to our code and our code works perfectly on other servers. I'm having trouble finding the issue, here's what happens:

• The filereference.upload is called, we provide all of the proper info - url, filename, etc
• The URL is http, and is correct. When visited through a web browser it works
• All debugging and tracing show that our code is running correctly
• The DataEvent.UPLOAD_COMPLETE_DATA evens never trigger
• The ProgressEvent.PROGRESS events never trigger.
• Server access logs and application traffic logs never show any requests coming to the upload script.

Based on all of this info, it seems that:

• Our script works fine, file.upload is called properly
• Event.OPEN is fired.
• Traffic never reaches the server
• No io/http errors are called.
• file.upload does return false, but it also returns false on servers that the upload works, and the complete events are called.

We're not using any firewalls or proxies on our end, and these tools work perfectly on other servers. But, these sites that are on the rackspace cloud sites all share this problem. However, a site that was in development a few months ago worked just fine on the same rackspace ckoud sites account. Trying the flash build from that version still won't work now.

How can I go about finding out what's breaking between the file.upload and the reaching the server?