Master & Cmd-R

Exchange Online Hybrid: Fixing free/busy issues

Now, I’m just going to come out and say it – this is NOT the only fix for free/busy issues when configuring Exchange Online Hybrid with an on-prem Exchange server. If you’re reading this, then it’s more than likely that you (like me), have been reading countless TechNet articles, blog posts, forum posts, etc. Well, at the end of it all, this was the fix for my free/busy issues, and I thought others might benefit by finding this ahead of time, and hopefully cut out some of the Googling Binging… 😉

The Problem:

Pretty straightforward – users on prem could not see the free/busy status of users in Office 365. I worked my way through every setting I could think of, including (but not limited to) Autodiscover, DNS, permissions, certificate settings, Exchange CU level, to no avail!

Also, if you haven’t seen this before, the hybrid environment free/busy troubleshooter was actually a great help in systematically working your way through potential problem spots.

The Solution:

Eventually, I came across this TechNet blog post which gave me the answer I needed – now, I will say that I’ve never had to set this before, and never noticed this setting missing on previous hybrid configs, but anyway…

In my on-prem environment, the TargetSharingEpr setting was blank, like so:

Thankfully, the fix for this is simple – run the following from an elevated PowerShell prompt:

Get-OrganizationRelationship | Set-OrganizationRelationship -TargetSharingEpr https://outlook.office365.com/ews/Exchange.asmx

This is what it should look like when you’re done:

I also checked my Exchange Online org settings and found that the TargetSharingEpr was also blank:

Now, I wasn’t having any issues with free/busy in this direction, but I thought I’d go ahead and update it anyway – just in case. Make sure that this time around, you’re connecting to Exchange Online, and not your on-prem Exchange, and point it back to your EWS endpoint:

Get-OrganizationRelationship | Set-OrganizationRelationship -TargetSharingEpr https://hybrid.mydomain.com/ews/exchange.asmx

(I don’t have to tell you that hybrid.mydomain.com needs to be updated to your own hybrid namespace, do I?) 😛

When you’re done, it should look like this:

There you have it – hope this helps someone else solve some free/busy issues without having to spend hours of frustrating trying everything else!


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Jeremy Dahl

Jeremy Dahl - Office 365 Evangelist

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