The error is not indicating a problem with your Forms trigger or the data you are sending. The important part of the error is:
Request to Graph API has timed out
Graph API is currently unavailable
504 Gateway Timeout / 502 Bad Gateway
The Excel Online (Business) connector uses Microsoft Graph/API services to access and update the workbook. So this appears to be either a transient Microsoft service issue or a problem accessing/processing the workbook, rather than a Power Automate formula/programming error.
A few things I would check:
1. Check the Excel file itself
Make sure the workbook:
Is stored in SharePoint or OneDrive for Business
Is not corrupted
Is not excessively large
Contains a properly formatted Excel Table
Does not have unnecessary formulas/calculations that could slow down updates
2. Make sure the workbook is not constantly open or locked
If multiple people have the workbook open and are editing it while the flow is writing rows, this can sometimes cause Excel connector problems.
Try closing the workbook for all users temporarily and test the flow again.
3. Check for multiple simultaneous Form submissions
Excel is not ideal for handling a large number of concurrent writes. If several Forms responses arrive around the same time, multiple Add a row into a table actions may try to update the workbook simultaneously.
If this is happening, consider controlling concurrency so that Excel updates are processed more sequentially.
4. Refresh the Excel connection
Try:
Going to Power Automate → Connections
Checking the Excel Online (Business) connection
Re-authenticating or recreating it if necessary
Then save and republish the flow.
5. Be careful when retrying failed runs
Your screenshot shows:
8 retries occurred
Before manually rerunning every failed flow, check the Excel table first. Sometimes the request can actually complete on the backend but Power Automate receives a timeout response. Retrying blindly could potentially create duplicate rows.
