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Home > Success Center > Patch Manager > Patch Manager - Knowledgebase Articles > WSUS synchronization fails with HTTP Error 503

WSUS synchronization fails with HTTP Error 503

Updated Oct 17, 2018


When you initialize an update task with WSUS, the following error appears:

HTTP Error 503. The service is unavailable.

The error may also appear when running a WSUS inventory task, the inventory may or may not be complete or partially complete.


Patch Manager


  • The WsusPool Application Pool in IIS is in a Stopped state. 
  • The Private Memory Limit (KB) for the Application Pool is set to the default value of 1843200 KB.


Consult with your systems administrator before you perform this procedure.

  1. Open the IIS Manager.
  2. Expand your site to find Application Pools.
  3. In the center pane, select WsusPool.
  4. In the Actions pane, click Start.
  5. Increase the Private Memory Limit to 4GB (4000000 KB). 
    1. Stop the EminentWare Data Grid Server Service.
    2. In the center pane, select WsusPool.
    3. Under Edit Application Pool, click Advanced Settings.
    4. Manually set the Private Memory Limit to 4GB (4000000 KB).
  6. Restart the Application Pool.
  7. Start the EminentWare Data Grid Server Service.


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