Get-WindowsUpdateLog

Troubleshooting steps - client

Check hard drive space

Check connectivity

Test-NetConnection -ComputerName <WSUS_Server> -Port 8530

WSUS settings

Get-ItemProperty HKLM:\Software\Policies\Microsoft\Windows\WindowsUpdate

Check event log

Application Event log as well as App and Service Logs > Microsoft > Windows > WindowsUpdateClient

Reregister client with wsus

gpupdate /force
wuauclt /detectnow

## Sometimes
wuauclt.exe /resetauthorization /detectnow

Troubleshooting problems - server

IIS Logs location

c:\inetpub\logfiles

references:

WSUS Troubleshooting Steps | Arnaud Loos
Common Windows Update errors - Windows Client | Microsoft Learn
WSUS Messages and Troubleshooting Tips | Microsoft Learn
Troubleshoot software update scan failures - Configuration Manager | Microsoft Learn