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Support Article

REST request malformed when query string param is blank



When the Connect-REST rule (JSON) has only a Single query string parameter and if the value of the parameter is blank, then the REST Request is malformed. This works if a dummy query string parameter is added to the Connect-REST rule.

For example:

The query string for the request is as follows:

Single parameter:





Two parameters:





Error Messages

HTTP Status: 400 Bad Request
Message: The request could not be understood by the server due to malformed syntax

Steps to Reproduce

  1. Use a REST Service that accepts only a Single query string parameter.
  2. Invoke the Connect-REST rule without passing a value for the query string parameter. This results in an error due to a malformed request.

    Resource path generated: 

Root Cause

A defect in Pegasystems’ code  or rules.


Perform the following local-change:

Set the pySkipBlankQueryParts parameter in the Request data transform.

Published May 12, 2019 - Updated October 8, 2020

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