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Support Article

Error displays in the browser console after upgrade



Error displays in the browser console after upgrade.

Error Messages

Error during WebSocket handshake: Unexpected response code: 501

Steps to Reproduce

  1. Log in to Designer Studio
  2. Open the browser console by clicking the F12 Key

Root Cause

A defect or configuration issue in the operating environment. 


Perform the following local-change:  
  1. Add the following Dynamic System Setting (DSS) if the Webserver version does not support WebSockets:
    Owning Ruleset: Pega-Engine
    Setting Purpose: prconfig/server-push/transport/default
    Value: long-polling
  2. Restart the server

The default value is 'websocket,long-polling' when the DSS is not present. With this setting, Pega only uses long-polling and does not attempt the WebSocket request.

Suggest Edit

Published September 20, 2018 - Updated December 2, 2021

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