Monday, May 8, 2017

New Hybrid Free/Busy Fails Cloud to On-Prem

When you configure hybrid mode, calendar sharing is automatically configured between on-premises and cloud users. You don't need to configure anything. However, in some cases, you may need to perform an IISreset.

On a recent project implementing implementing hybrid mode for an Exchange 2010 organization, we enabled hybrid mode and tested connectivity. Everything looked good for mail flow and mailbox moves. However, free/busy lookups failed from the cloud users to on-premises. When we tried to view the on-premises users' calendars the status was "No Information".

When you're not sure what's going on, it's always a good idea to use the Remote Connectivity Analyzer to test things out. There is an Office 365 tab which includes a Free/Busy test. When I ran this test, it was successful, as shown in the figure below. However it still wasn't working.

It's been a while since I've implemented Hybrid for Exchange 2010. With a quick search, I found this blog post that reminded me that an IIS reset will fix this up:
Most Exchange IIS related issues resolve themselves after a period of time. That period of time might be 12-16 hours, but usually there is some background process that refreshes things.

In this case, hybrid mode had been configured for multiple days. The free/busy lookups required an IISreset or a server reboot to fix.

This fix is certainly relevant for Exchange Server 2010. It may also be relevant for later versions of Exchange Server.

1 comment:

  1. THANK YOU for taking the time to post this. I just spent several hours trying to figure out why free-busy o365 -> onprem was failing.

    While I found a lot of interesting places to look from the an MS troubleshooter article (and many other posts), nothing solved it - everything looked good. Good old IISRESET fixed it immediately (only setup hybrid coexistence earlier today so no restarts of IIS or the server yet).