June 2017 Security Update Breaks Outlook Search

The June 2017 security update for Windows causes problems for search in Outlook clients using cached mode.  Uses will see incomplete search results and may be notified that:

Search results may be incomplete because items are still being indexed.

This issue affects Windows 7, Windows 8.1, and Windows 10. It also affects all versions of Outlook.


Microsoft has fixed this issue with a new update released on June 27th. You can download the update here:

• Windows 10 - KB 4022716
• Windows 8.1 - KB 4022720
• Windows 7 - KB 4022168

These fixes are for retail, OEM, and volume licensed versions of Outlook. If your Outlook is included with an Office 365 version of Microsoft Office, then updates are already available and should be installed automatically. If they are not installed automatically performed the following steps:

1.  In Outlook, click the File tab, and click Office Account.
2. Click Update Options and click Update Now.

To review Microsoft's documentation on this issue, see Issue #5 on this page:

•  Outlook known issues in the June 2017 security updates

Outlook 2016 - The connection to Microsoft Exchange is unavailable

This is a unique scenario, because it applies primarily to testing environments. I have a lab setup with Exchange Server 2016 and Outlook 2016. I was going a bit nuts because each time Outlook 2016 tried to configure the profile I got the following error message:

The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action.

This error can occur when you get names wrong in your internal or external URLs. So, I verified the names in all of my internal and external URLs. I also tested connectivity in Outlook and the URLs from Autodiscover were correct. Also verified the names in the certificate.

It turned out to be an issue with the default gateway. As part the connection process, Outlook 2016 was attempting to connect with the default gateway (which didn't exist on my test network). When connectivity to the default gateway failed, Outlook provided that error.

To fix this, I pointed the client running Outlook 2016 at a valid IP for the default gateway. I used the IP of my domain controller. It's not important whether it's a router or not, it just looks for an IP that is alive. I've been too lazy to put a packet sniffer on it yet. I'm just happy it's working.

Short version: Make sure clients running Outlook 2016 have a valid default gateway.

Note: Credit to Stan Reimer who actually gave me the fix after it was discovered during development of a Skype for Business course

Update: For an explanation of why this happens, see this post: http://blogs.technet.com/b/rmilne/archive/2014/03/27/outlook-unable-to-connect-to-exchange-_1320_default-gateway-not-found.aspx