Error [System error: An error occurred while communicating with data source 'LoomDataSource'] Occurs When Changing the Value of a Pivoted Column After the Pivot Step

Published: 22 Feb 2023
Last Modified Date: 24 Feb 2023


The below error shows up when changing a value in the pivot field after the pivot step:

System error: An error occurred while communicating with data source 'LoomDataSource'

For example, add a Clean step after the Pivot step, and the data type of the Pivot1 Names field is String.
User-added image
However, after double-clicking "2016" in the Pivot1 Names field and inputting "11111" to change the value, the error occurs.
User-added image
User-added image


  • Tableau Prep Builder 2022.4


Please try the below workarounds to avoid this issue.

Option 1

Use an earlier version of Tableau Prep such as 2022.3.3.  To obtain specific downloads please visit the Tableau Release Notes page website.

Option 2

After the Pivot step, perform the following:
1. Change the data type in the Clean step.
2. Change the value of the pivoted field.

For example, for the screenshot above, no error occurs when changing the data type to String or Date first and then changing the value from "2016" to "11111".

Please also review the attached flow for more details.


This issue is under investigation with Tableau Prep Known Issue ID 1499968.
Did this article resolve the issue?