KB-2158 Process variables unexpectedly set to null after asynchronous sub-process runs


Process variables are unexpectedly set to null after an asynchronous sub-process node completes, even though non-null output is expected:


The asynchronous sub-process has output variables that were not deleted because it was once synchronous. When the process became asynchronous, the output variables became hidden but were not removed. This caused the parent process variables mapped to the output variables to become nullified instead of remaining unchanged after the asynchronous process ran. This issue has been reported to the Appian Product Team with reference number AN-96059.


  1. Convert the sub-process back to synchronous.
  2. Remove the output variables.
  3. Convert the sub-process back to asynchronous.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: October 2020