On 10 February 2016 Microsoft posted a notice to remind customers that Exchange is not compatible with the .NET Framework 4.6.1 that was recommended as an update on 9 Feb 2016. In fact, there are known issues if the new version is installed.

The Exchange Team blog post told Exchange customers to delay upgrading to .NET Framework 4.6.1, and updated their post 12 Feb 2016 to provide the steps to roll back to .NET Framework 4.5.2 if the update took place. You can read the post here: http://blogs.technet.com/b/exchange/archive/2016/02/10/on-net-framework-4-6-1-and-exchange-compatibility.aspx.

LOGbinder is targeted to .NET Framework 3.5 for compatibility reasons. Many customers reported issues when we targeted 4.x.