Following sites not working in a Hybrid Sites scenario – 401 Unauthorized

Earlier this week, I was at one of my customers which has a SharePoint 2013 implementation. They had an issue where following sites was not working anymore. When they clicked the Follow link, they got an error that the site could not be followed.

They have a hybrid implementation with OneDrive for Business and Hybrid Sites setup.
When I looked in the ULS, I saw the following error popping up

Loud and clear… authentication issues.

Microsoft has an excellent resource where they outline the roadmap to implement hybrid features.

Both roadmaps outline the steps which are needed to set up those features. Since OneDrive for Business was working fine, I focused on the Hybrid Sites features and started going through the steps of the roadmap to see if everything was set up correctly.

  1. Configure Office 365 for SharePoint hybrid – Check!
  2. Set up SharePoint services for hybrid environments – Check!
  3. Install the September PU for SharePoint Server 2013 – We were on the December 2016 CU, so … Check!
  4. Configure S2S authentication from SharePoint Server 2013 to SharePoint Online –  Hmmm… I don’t recall doing this in the past.
  5. Configure hybrid sites features in Central Administration – Check!

Since I was getting authentication issues, and I didn’t recall me doing the S2S authentication configuration step, I figured that this was the cause of the problem.

When you follow the link for that step, you will see that there’s some work to do to set it up. Luckily, Microsoft provided a tool which actually does it for you. It’s called the Hybrid Picker. This simplifies things a bit.

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Getting Sync To Outlook to work in SharePoint 2013

Earlier this week, a customer requested me to look into an issue they had with the “Sync To Outlook” functionality in SharePoint 2013.

When you click that buttton in the ribbon when you are on a tasks list, you get a popup where you can “check” a checkbox  to “Sync tasks”. When everything works, the popup will disappear and it’s done. But everytime they tried it, they got the message :

“We weren’t able to start syncing your tasks because one or more pre-requisites for connecting to Exchange Server could not be found. Please contact your administrator”

To get this working, there are indeed some pre-requisites. All of them can be found in the following article:

Configure Exchange task synchronization in SharePoint Server 2013

I started to look at the requirements and quickly noticed that everything should be OK.

So, I decided to have a look at the ULS. The message which appeared also includes a correlation ID. Hoorah!

Opened my ULS Viewer on the WFE and looked for all entries for the correlation ID I got. Disappointment… not a single hint of something going wrong.

Perhaps on the other servers?

I opened the created file and hello!!! There were a lot more entries than I expected. Most of them were coming from the APP server and one of them was the one I needed…

02/25/2014 09:37:00.43 w3wp.exe ([APPSERVER]:0x0DE0) 0x100C SharePoint Portal Server Exchange Task Synchronization ah8z3 Medium Exchange sync – Missing Exchange Managed API library d7a5779c-6452-8013-6174-40db0fdedf78

The Exchange  Web Services API was missing … on the APP server. I replaced the real name of the server above with [APPSERVER]. And this was indeed correct since the article specified that you need to install this on each WFE.

There’s a nice white paper from Microsoft which explains how the My Tasks Aggregation and Exchange Task aggregation works and after reading this I’m starting to think that it’s not specifically the WFE where the Exchange Web Services API has to be installed but the server where the Work Management Service is running.

After installing the Exchange Web Services API and doing an IISRESET, the error disappeared and the sync was working.