Microsoft released Exchange Server 2016 CU6 a few days ago.
In this tutorial we will go through the steps of running the upgrade. For a list of fixes etc. you can refer to the link below:
Take note that there is a Schema update in this CU. Let’s proceed..
We have included a number of screenshots, not all of them but you can see in Step 1 the install the Organization Preparation is done (Schema Update). You should run the command setup /PrepareAD and /PrepareSchema before proceeding with the installation. We ran the PrepareAD command already but wanted to show you the install does the Schema upgrade before it proceeds.
After about 1.5 hours the upgrade completed.
Post installation, opening outlook and my test client successfully connected without issue:
Hope it helps.