This behavior has been seen when:
When uninstalling WSUS Role via ARW the “API and PowerShell cmdlets” feature is not uninstalled by default (unless explicitly selected by the user). Deleting the remaining WSUS folders and registry keys leaves the server in a bad state and the re-installation fails because it is expecting this feature to be already installed.
Uninstall all the WSUS roles and features and re-install WSUS.
Workaround 1: To uninstall WSUS roles and features using Windows PowerShell
Workaround 2: To uninstall WSUS roles and features using the Server Manager Console
In Server Manager, launch Remove Roles and Features Wizard (RRW), unselect items to be uninstalled, and complete the Wizard:
We recommend restarting the server to ensure that all WSUS components are removed. After uninstalling WSUS roles and features, you may reinstall the WSUS roles and features.
To reinstall WSUS, launch the Add Roles and Features Wizard and then select the “Windows Server Update Services” option. You may optionally reinstall the Windows Server Update Services Tools. After the ARW completes successfully, you may run the WSUS post-installation tasks.
Thank you very much. I was trying to do a clean reinstall of WSUS ran into this problem after uninstalling and doing the manual deletions. Your work arounds took me a couple ties because I when I clicked remove WSUS in the ARW it has a pop up windows to remove features related to WSUS. I though this was your step 2 but it is not. I still needed to do your step 2 and once I did it worked. Thank you again this has fix several days of frustrations
very good article indeed thank you
This worked for me. Thanks.
Awesome, it took forever to find out root cause. Thank you for article
Guys for some reason I am unable to install WSUS on my Server 2012 R2. It keeps error-ing out saying Post Installation Failed. This is a brand new server, new install. The only thing on it is Symantec. What am I doing wrong? I got machines I cannot update...so