Posted by: David | October 24, 2010

Exchange 2007 Outlook Anywhere rpcproxy.dll HTTP 500 Response

Here are a few notes from an issue I came across this week with an exchange server configured for Outlook anywhere. For what ever reason Outlook Anywhere stopped working and the RPC over HTTP clients were no longer able to connect.

After checking all the norms, like certificates and firewall rules I ran the tests on this is an awesome site (although from experience little known) which can remotely test most aspects of exchange.

After running the test it came back with the following results:

Testing Http Authentication Methods for URL
The HTTP authentication  test failed.
Additional Details An HTTP 500 response was returned from  Unknown

After some googling I stumbled across  the following forum post, it advised that you check the SSL settings on the RPC virtual directory, I meet the following requirements:

  • Require SSL (Checked)
  • Require 128-bit SSL (Unchecked)
  • Client certificates: Ignore

If you are still having problems you may need to reinstall the RPC Proxy component on the CAS server. Below is the procedure for fixing this (This was taken from the above mentioned forum post)

  • Disable outlook anywhere via EMC
  • Remove RPC proxy component via PowerShell
  • Command: servermanagercmd -r rpc-over-http-proxy
  • Reboot the server
  • Install RPC proxy component via PowerShell
  • Command: servermanagercmd -i rpc-over-http-proxy
  • Enable outlook anywhere
  • Restart Microsoft active directory Topology service

After this RPC was working for existing users but could not be set up for new users. The retest on the the RPC passed but overall tests still failed with an ERROR performing an RPC Ping on 6004, the referral on the site was to the following page,

Here there were a number of things to check including checking some registry settings and making sure the front end sever could ping the CAS server using both Netbios and FQDN, in this case there was only one server running all roles. There was also a listed known issue with IPv6 on versions of Exchange 2007 pre SP1 RU4. Well this server was running SP3. Upon pinging via Netbios and RPC I noticed that the server name was resolving to a self assigned IPv6 address. After removing IPv6 from the server LAN adapter (no reboot required) the server name was now resolving to the IPv6 loopback interface.

I modified the local hosts file to put the FDQN and Netbios names to the IPv4 address and tested, they were now resolving with the IPv4 addresses. Checked on

There are a number of ways of completely disabling IPv6 on Server 2008 and on the next maintenance window I shall be looking in to the best way to do this and update the post at that point.


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