Environment Details
- Alteryx Designer
- Output data tool
Cause
When writing out a new spreadsheet, the file name does not contain a sheet name.
Resolution
Update the filename to include a sheet name. For example, append the sheet name using three pipe characters (|||) as the delimiter; or try reselecting the file in the Write to File or Database drop down, and it can prompt a sheet name option (in the second image below). For more information, see the Output Data help page.

