Lync 2010 Group Chat - Can't upload files during chat: "A file transfer error occurred. The request failed with HTTP status 404: Not Found."

My path to getting both Lync Server 2010 working, and the Group Chat add-on role, has been long and painful. But by and large I am finally there. Everything works, with Lync clients signing in, as well as Group Chat clients. Communication works soundly in the chat room I've created as a test.

But if I try to upload a file in this chat room, I get the error message in my question title. There is lots of info on the web concerning this, and I have followed every guide to ensure anon access is enabled, set the OCSChannel account to run this, bind the https port 443 with the correct certificate for the default website that houses the chat web app, and ensure ACL lists are correctly filled with the OCSChannel on both the web app folder, and the folder that acts as the share for the uploaded files.

The one bit of info I picked up that could be meaningful is that Group Chat shouln't be installed on the same server as Lync Server itself, as they will compete for the binding of port 80 & 443. However, according to the Microsoft deployment guide, all on one server is supposed to be fine!

Does anyone have some suggestions as to what I might do? Having got this far, the thought of setting up an entirely new VM and running Group Chat in there doesn't fill me with joy. I'd rather get this working in place. If it is an issue with the bindings, can I change the port 80 & 443 to something else for the internal Lync web apps?

I appreciate any thoughts.

Many thanks :)
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bluemercuryAuthor Commented:
Worked this out for myself, and leaving the answer here to benefit anyone else.

My suspicions were correct - you cannot run the Group Chat role on the same server that houses Lync Server. They will compete for ports on the web server side of things, and file exchange won't therefore work (as this is depedent on IIS / http).

I set up a completely seperate Windows 2008 R2 server in a VM. I still had lots of problems getting set up, but I got there eventually. You need to get a certificate issued (for both the IIS web server and for the Group Chat role) for the group chat server name, from the same certificate authority as your Lync server. You also need to add an additional trusted computer pool on the Lync Server (mine is Standard edition, this step might not be needed if you are running enterprise servers already in a pool, and can add this further server to the trusted list - not an option in Standard edition).

I then set up the Group Chat server otherwise as per ther Microsoft Group Chat deployment guide, and when prompted for a certificate used the one that had been issued for the local server. At the end of it all, I had a working internal Group Chat server :)

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