Issue:
One of the Sharepoint App Servers is showing Upgrade Required within the Farm Information on the Central Admin site.
I had run the Upgrade command successfully, and checked within Central Administration and it was still showing Upgrade Required.
Re-ran the Upgrade just incase and same result.
Solution:
A nifty Sharepoint trick so that Sharepoint will go and do a fresh update and check of the binaries.
Get-SPProduct –Local
To check the Farm Version, run the below:
$farm = Get-SPFarm
$farm.BuildVersion