WSUS is not a valid Win32 application! (Config Manager)

Today we had an odd message in System Center 2012 – Configuration Manager.

Software updates synchronization for the Software Update Point role failed

We had also been experiencing problems relating to ConfigMgr client deployments – they would install, but stick with only 4 or 5 options (Machine Policy Retrieval & Evaluation Cycle, Software Updates Deployment Evaluation Cycle, Software Updates Scan Cycle, User Policy Retrieval & Evaluation Cycle).

I had a look in Server Manager, and sure enough the WSUS Service (Yes – the ‘Windows Server Update Services.. Service) was stopped. Clicking Start resulted in a wonderfully helpful message:

Windows could not start the WSUS Service service on local computer.

Error 193: 0xc1

(Notice how we’re now up to three “services”?! :P)

Anyway, a quick trawl through eventvwr yielded:

The WSUS Service service failed to start due to the following error:

WSUS Service is not a valid Win32 application.

The problem appears to be related to a PXE Provider (WDS Server) installation through ConfigMgr – at some point during the installation, it seems to create a file in the C Drive called ‘program’ which blocks access to the ‘real’ Program Files folder.

Removing the “C:\Program” file (or renaming it if you’re jumpy), and then restarting WSUS fixed the issue.