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Null parameter error when tracing a case during its creation



Null parameter error occurs when tracing a case during its creation.

Error Messages

Required parameter ... for data page ... cannot be blank.

Steps to Reproduce

  1. Configure an autocomplete field with a data page as the source
  2. Retrieve the data page values from a data transform
  3. Create a case and navigate to the Tracer

Root Cause

Pega 7.3 uses the Change tracker mechanism which loads a data page and other rules while case creation and logs the case in the Tracer. The following code snippet in the tracker results in the error:

try {
if (tools.getParamValue("AJAXTrackID") != null
&& !tools.getParamValue("AJAXTrackID")
.equals("")) {
com.pega.pegarules.priv.runtime.IStreamChangeTracker ct_controlAction = pzAuto
true, -1);
} catch (Exception e) {


Perform the following local-change:
  1. Create a new data transform, for example, testDT and set the following:
    Param.role to "aaaar"
    Param.orgUnit to "bbbb"
  2. Set 'Apply Data Transform' as testDT in the flow action tab

Published March 29, 2018 - Updated October 8, 2020

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