Fixing “Unable to load task handler … for task …” in VSTS/TFS 2015 build

Last week I introduced a client to the new TFS 2015 build system. They happily started experimenting with it, but soon ran into a bit of a cryptic error message saying “Unable to load task handler … for task …”.

It turns out that the solution was pretty simple: the version of PowerShell that’s running on the build agent machine needs to be at least version 4.0. You can easily check this by typing “$PSVersionTable” in a PowerShell window. The “PSVersion” should read at least 4.0.

After upgrading the PowerShell version on the build machine, all was fine!

You can download the Windows Management Framework, which includes PowerShell, here:

• Windows Management Framework 4.0:
• Windows Management Framework 5.0:

I hope this helps!

Happy building!