The Exchange Team posted a quick note Tuesday addressing the release of .NET Framework 4.7 and Exchange. As of right now (June 2017) .NET 4.7 is not supported. While the Exchange team has not documented any known compatibility issues (like we saw when previous releases first shipped) they report the update has not been fully tested with Exchange and recommend all customers block the update until further notice.
As with any series of patching it is always critical to review all updates against the Exchange Supportability Matrix. If you want support from Microsoft you must be within the boundaries of that matrix. At the time of writing .NET 4.6.2 is the latest version supported by Exchange 2013 and Exchange 2016, provided you are on the latest cumulative updates. Older cumulative updates only support older versions of .NET. The Exchange Supportability matrix states that any version of .NET not listed on that site should be considered unsupported.
If you have already applied .NET 4.7 to your Exchange servers the product group recommends rolling back. They have identified this process in their latest blog post.
For an environment that uses patch management software such as WSUS or System Center, it is always a good idea to put Exchange servers in their own update group. This allows you to isolate Exchange into its own update cycle. If you don’t have a patch management system you can temporarily block .NET through the registry. Although this registry change will need to be performed against each Exchange server.
With future cumulative updates .NET Framework 4.7 will eventually be supported. We will update this space when this occurs.
Do you think Exchange should have day-one support for the .NET Framework? Join the conversation on Twitter @SuperTekBoy.