Sysadmins of the North

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WsusPool keeps crashing: stops again and again

Sometimes you find your WSUS server keeps crashing over and over again. WSUS is unavailable and/or the WSUS management console hangs. When you start to investigate as to why Windows Server Update Services crashes, you’ll notice the following error message being logged in the HTTPErr log files:

2017-05-08 05:03:53 56433 80 HTTP/1.1 POST /SimpleAuthWebService/SimpleAuth.asmx 503 707060612 AppOffline WsusPool

In the Eventlog you might find errors indicating that the WSUS administration console is unable to connect to WSUS Server via remote API:

The WSUS administration console was unable to connect to the WSUS Server via the remote API.

Verify that the Update Services service, IIS and SQL are running on the server. If the problem persists, try restarting IIS, SQL, and the Update Services Service.

Sometimes clients checking for Windows Updates would quickly error out with a code 0x80244021, which indicates the inability to reach WSUS.

How to improve Windows Server Update Services (WSUS) availability

To improve WSUS availability, you need to increase IIS Private Memory Limit. The default limit is set to 1843200KB. And when an IIS worker process uses more than 2GB, WSUS crashes and the problem occurs.

Change Private Memory Limit (KB) to a higher number that fits your server specifications or simply , which means no limit, instead of the hard-coded 1843200.


Follow this path to find the setting:

WSUS Application Pool IIS Advanced Settings
WSUS Application Pool IIS Advanced Settings

Internet Information Services (IIS) Manager → Server → Application Pools → Select “WSUSPool” → Actions Advanced → Recycling → change “Private Memory Limit (KB)“.

This’ll improve WSUS availability.

A second approach may be to set Enable 32-Bit Applications to False in the Application Pools Advanced Settings. This’ll disable the 32-bit mode for WSUSPool, and forces it to run 64-bit. Be sure to have an ISAPI Filter set for 64-bit Framework as well!

  • Open IIS Manager on the WSUS server.
  • Browse to the website being used by WSUS. Depending on the WSUS configuration, this will typically be either the Default Web Site or a site named WSUS Administration.
  •  Double-click ISAPI Filters.
  • Right-click the entry that corresponds to ASP.Net v4.0 (the specific version number may vary) and select Edit.
  • In the executable path, replace the name of the Framework folder with Framework64 and click OK. Do not change anything else in the file path.
  • Restart the website, then verify that the WSUS Administration console is able to connect to the WSUS server.


Learn how to clean up WSUS, how to re-index the WSUS 3.0 database, and how to get the WSUS version in PowerShell (thanks to Johan de Haan @ Serverfault):

$wsus = [Microsoft.UpdateServices.Administration.AdminProxy]::getUpdateServer("wsus-server",$False)

Want to say thanks?

If I’ve helped you out and you want to thank me, why not buy me a coffee?

If I’ve helped you out and you want to thank me, why not buy me a coffee?

Thank you for your support. ♥


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  1. Christian

    This fixed my issue!


  2. Unfortunately, this does not resolve the issue for my installation. I’ve tried using the console on the server, and using the remote console on my computer. I still get timeout errors even with 24GB of RAM and a fresh reboot of the server.

  3. Ian Simons

    I WISH I had found this post before constantly having to remove/reapply the WSUS role to our server – this issue has been bugging me off and on for a couple of years now. Increased the AppPool memory to 8GB and ZAP! instant performance! Thank you SO much for this.

  4. Alex Gibson

    This tweak is essential for the product to work correctly. Only the most minor of reporting was available to us w/o implementing this change on our WSUS Server 2016.

    Thank you very much for discovering and writing this up.

  5. Jack H

    Still relevant July 2018 on Server 2016. THANK YOU.

  6. Steve

    Phew, I could’ve sworn I’d changed this setting on the server, turns out I hadn’t, set it to 0 and no more 503 errors, thank you!

  7. KB

    You are the Man!

  8. Andrea Soc

    I love you ! thanks , you are solved my frustating problem..

  9. Anonymous

    This worked for me. Thanks!

  10. O.V

    Thanks, Man. Your solution has saved the day!

  11. Alex Felipe

    Thanks for this post, I’ve been this same (boring) problem.

  12. Anonymous

    This is a good post! thanks…

    I’ve been looking for this answer

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