I was asked by a customer to introduce a new Hyper-V 2012 R2 core mode node into an existing cluster.
As always I checked the existing nodes for Windows updates and patched the new node accordingly. The Add node menu item was using in the failover cluster manager and all tests had been selected. Quickly the validation failed with the error below.
Upon closer inspection we can see that the Microsoft DSM version doesn't match! So Windows update was used to check for missing updates, but both nodes showed no updates available.
I used PowerShell to compare the MSDSM.SYS files on both systems, and as we can see below the FilePrivatePart is newer.
I Googled about to find out if there was a hotfix that might have updated the MSDSM.SYS file but no joy.
In the end we narrowed it down to the fact that the March preview update has updated the file. After rolling this out to all cluster nodes the validation passed and the new node was added.