In addition to the above, attempts to access the URL for the WSUS Administration website (i.e., http://CMCASSERVER:8530) fails with the error:
In this situation, the most likely cause is that the WsusPool Application Pool in IIS is in a stopped state, as shown below.
Also, the Private Memory Limit (KB) for the Application Pool is probably set to the default value of 1843200 KB.
If you encounter this problem, increase the Private Memory Limit to 4GB (4000000 KB) and restart the Application Pool. To increase the Private Memory Limit, select the WsusPool Application Pool and click Advanced Settings under Edit Application Pool. Then set the Private Memory Limit to 4GB (4000000 KB).
After the Application Pool has been restarted, monitor the SMS_WSUS_SYNC_MANAGER component status, wcm.log and wsyncmgr.log for failures. Please note that it may be necessary to increase the Private Memory Limit to 8GB (8000000 KB) or higher depending on the environment.
Now WSUS is back online!