Exchange 2010 SP1 CAS server event ID 1033

After moving into the testing phase of the 2010 sp1 deployment I have started noticing a multitude of 1033 errors on the four CAS servers in the CAS array.

Source service is MSExchActiveSync


It turns out that the web.config file is missing an entry for the "ExternalProxy" setting. Which is fine if you don't use it.

To make the error go away add this entry to your web.config file and do a iisreset /noforce; which make take a while in a production enviroment. In fact you may need to drainstop the particular CAS sever from in the NLB service first to get the active connections to 0 and thus iisrest /noforce works.

For the code to insert in the web.config file see this thread:

http://social.technet.microsoft.com/Forums/en-US/exchange2010/thread/7a308dcc-56b2-4c29-a586-7b476b913998