Bug: Radial/Sankey chart in Show Me corrupts workbook (Error D2E8DA72) even after Undo

Summary: 

Clicking on the Radial or Sankey chart type in the "Show Me" panel — even briefly, and even if immediately undone — permanently corrupts the workbook file. Saving and reopening the file afterward fails with Error Code D2E8DA72. 

Environment: 

- Tableau Desktop, Professional Edition 

- Version 2026.2.0 (20262.26.0603.1643) 

- Windows 

Steps to Reproduce: 

1. Open any workbook (new or existing) in Tableau Desktop 2026.2.0 

2. Select a worksheet and open the "Show Me" panel 

3. Click on the Radial (or Sankey) chart type once 

4. Immediately press Ctrl+Z (Undo) 

5. Save the workbook as a packaged .twbx file 

6. Close Tableau Desktop 

7. Reopen the same .twbx file 

Expected Result: 

The workbook should open normally, since the chart type was undone and never appears on any sheet. 

Actual Result: 

Tableau fails to load the workbook with the following error: 

Error Code: D2E8DA72 

Error: no declaration found for element 'worksheet-extension' 

Error: attribute 'extension-version' is not declared for element 'worksheet-extension' 

Error: attribute 'id' is not declared for element 'worksheet-extension' 

Error: element 'worksheet-extension' is not allowed for content model '(document-format-change-manifest,(dashboard-extension),resources?)' 

Root Cause (as far as I can diagnose): 

Even though the chart action is undone and never persists visibly in the workbook, Tableau still writes a <referenced-extensions> manifest block into the underlying .twb XML the moment the chart type is clicked. This manifest references the built-in extension (e.g. com.tableau.extension.radial) but appears to be incompatible with the workbook's own internal file-format version, causing Tableau's own XML validator to reject the file on the next load. This happens even in a workbook that never uses the chart on any actual sheet. 

Workaround (manual): 

1. Rename the .twbx file to .zip 

2. Extract the zip 

3. Open the .twb file in a text editor 

4. Search for "referenced-extensions" 

5. Delete the entire block from <referenced-extensions> to </referenced-extensions> 

6. Save the .twb file 

7. Re-zip the .twb file along with the Data folder 

8. Rename the new zip back to .twbx 

The file then opens normally with no loss of dashboard content. 

Impact: 

This is a significant reliability risk since: 

- It occurs with no warning at the time the chart is clicked or undone 

- It can silently corrupt a file that appears completely fine until the next reopen 

- It could affect students/professionals submitting workbooks for grading or review, since a file that worked when last saved may fail to open for the recipient 

I'm happy to share the exact corrupted and fixed .twb/.twbx files if useful for reproducing or debugging this on your end.