11.02.2016     Follow me on Facebook
by Edgar Gierth

.Net Framework 4.6 is not supported on any Exchange Server version until now

Microsoft has released .Net Framework 4.6 with latest patch day


Microsoft has released .Net Framework 4.6 with latest patch day, but versions of .Net Framework 4.6 are not supported on Exchange Servers until now! The Microsoft Exchange team has issued a warning to customers to not install .NET Framework 4.6.1 on Exchange servers.

Microsoft Exchange support matrix.

Possible issues

1. Mailboxes could be quarantined unexpectedly
2. Databases could be unmounted unexpectedly
3. Databases could be made failovers unexpectedly

Microsoft knowledgebase article 3095369.


Uninstall .Net Framework 4.6

If .Net Framework 4.6 is already installed on Exchange 2013 servers, it could be unistalled:

1. If the server has already automatically updated to 4.6.1 and has not rebooted yet, do so now to allow the installation to complete
2. Stop all running services related to Exchange. You can run the following cmdlet from Exchange Management Shell to accomplish this: (Test-ServiceHealth).ServicesRunning | %{Stop-Service $_ -Force}
3. Go to add/remove programs, select view installed updates, and find the entry for KB3102467. Uninstall the update. Reboot when prompted.
4. Check the version of the .NET Framework and verify that it is showing 4.5.2. If it shows a version prior to 4.5.2 go to windows update, check for updates, and install .NET 4.5.2 via the KB2934520 update. Do NOT select 4.6.1/KB3102467. Reboot when prompted. If it shows 4.5.2 proceed to step 5.
5. Stop services using the command from step 2. Run a repair of .NET 4.5.2 by downloading the offline installer (https://www.microsoft.com/en-us/download/details.aspx?id=42642), running setup, and choosing the repair option. Reboot when setup is complete.
6. Apply the February security updates for .NET 4.5.2 by going to Windows update, checking for updates, and installing KB3122654 and KB3127226. Do NOT select KB3102467. Reboot after installation.
7. After reboot verify that the .NET Framework version is 4.5.2 and that security updates KB3102467 and KB3122654 are installed.

Block .Net Framework 4.6 updates

If .Net Framework 4.6 is not already installed on Exchange 2013 servers, or you have unistalled .Net Framework 4.6 xou couls block this update:

1. Back up the registry.
2. Start Registry Editor. To do this, click Start, type regedit in the Start Search box, and then press Enter.
3. Locate and click the following subkey: HKEY_LOCAL_MACHINE\Software\Microsoft\NET Framework Setup\NDP
4. After you select this subkey, point to New on the Edit menu, and then click Key.
5. Type WU, and then press Enter.
6. Right-click WU, point to New, and then click DWORD Value.
7. Type BlockNetFramework461, and then press Enter.
8. Right-click BlockNetFramework461, and then click Modify.
9. In the Value data box, type 1, and then click OK.

Microsoft knowledgebase article 3133990.