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.

Comments

  1. Joshua McKinnonAugust 11, 2017 at 11:17 PM

    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).

    ReplyDelete

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