A 400 error means that the request sent to Google Sheets was rejected because something about it was invalid. The most common cause we see is that the target spreadsheet is not a native Google Sheets file.
Imported Excel files (compatibility mode)
If your spreadsheet was originally created as an Excel file (.xlsx) and uploaded to Google Drive, it may still be running in compatibility mode rather than as a native Google Sheet. You can usually tell because the filename will still show the .xlsx extension, or you may see a green "E" icon instead of the standard Google Sheets icon.
Google's API handles these files differently, and Shopify Flow can fail to write to them with a 400 error.
To fix this:
Open the file in Google Sheets and go to File > Save as Google Sheets. This will create a native Google Sheets copy. Use this new file as the target in your Shopify Flow action.
Please note:
The new file will have a different URL and file ID, so you will need to update your Flow to point to it.
Other possible causes
While the compatibility mode issue above is the most common reason for a 400 error, it can also occur if:
The worksheet tab that your Flow is targeting has been renamed or deleted.
Columns in the spreadsheet have been renamed, removed, or reordered since the Flow was set up.
The spreadsheet is approaching Google Sheets' 10 million cell limit.
Required fields in the Flow action have been left blank or contain data that the API cannot process.
If none of the above resolves the issue, please get in touch and we can take a closer look.