When checking the status of a software update deployment under the monitoring section, you can notice that SCCM clients are listed into the “Unknown” tab. Status is “Client check passed/Active”.
When you check wcm.log, you can see the following error message:
The request failed with HTTP status 503: Service Unavailable.
or in the “windowsupdate” log file:
The body of the received message contained a fault.
You also can see the following error codes:
The Private Memory Limit (KB) for the Application Pool is set to the default value of 1843200 KB which is not enough.
If you encounter this problem, increase the Private Memory Limit to 4GB (4000000 KB) and restart the Application Pool named “WSUSPool”.
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