File Cannot Open

How to Fix Excel Backup Files Created by Power Automate Not Opening

Kushani Nimanthika Oct 12, 2026 869 views

Question details

The user needs to fix an issue where Excel backup files generated by Power Automate cannot be opened due to file-format mismatch errors.

Fix Excel Backup Files Created by Power Automate That Will Not Open

Product: Microsoft Excel, Power Automate
Device & OS: not provided
Scenario: Automatically creating Excel backup files in a document library using Microsoft Power Automate flows.
Observed behavior: The generated .xlsx file produces a file-format mismatch error upon opening, indicating that the flow saved invalid file content or corrupted data.

Before you start

Ensure you have editing permissions for the Power Automate workflow and verify that the original source Excel file is intact and not corrupted.

Solution 1Recommended

Correct the Power Automate Flow to Save Binary Content

Modify your flow to ensure it retrieves and passes the actual binary content of the Excel workbook rather than invalid file metadata.

A common mistake in Power Automate is passing item properties or metadata instead of the actual file content to the file-creation action. This results in a file that has an .xlsx extension but contains plain text or JSON data, which Excel cannot read.

Edit the Power Automate workflow

Add or verify the 'Get file content' action

Ensure there is a 'Get file content' action targeting the original Excel workbook before the backup creation step.

Map the File Content properly

In your 'Create file' action for the backup destination, click on the 'File Content' field. Use the dynamic content panel to select the 'File Content' output directly from the preceding 'Get file content' action.

Verify file name and extension

Confirm that the 'File Name' field in the 'Create file' action ends with the '.xlsx' extension.

Test the flow

Save your workflow, trigger a new run to create a fresh backup file, and attempt to open the newly generated file in Excel.

Correct the Power Automate Flow to Save Binary Content

Previous Files Cannot Be Recovered: Adjusting the flow will only ensure future backups are created correctly. The already corrupted backup files containing invalid data cannot be repaired.

Solution 2

Test File Extension and SharePoint Destination

Verify if the corrupted file can force a format recognition, though generating a new backup is usually required.

Free Microsoft Office alternative

Try WPS Office for Seamless Spreadsheet Management

If you frequently encounter compatibility or file format errors with Microsoft Office, try WPS Office. It provides a lightweight, highly compatible, and free alternative to easily view, edit, and back up your spreadsheets without the heavy resource usage.

1. Download WPS Office: Visit the official WPS Office website and download the free installation package.
2. Install the software: Run the installer and follow the on-screen instructions to complete the setup.
3. Open your spreadsheets: Launch WPS Spreadsheets, click 'Open', and select your Excel files to enjoy seamless editing.

Fully compatible with Microsoft Excel formats (.xlsx, .xls, .csv).Easily open and inspect automated backup files with high compatibility.Lightweight design ensures fast loading and smooth performance on any device.Familiar user interface for a seamless migration from Microsoft Office.

microsoft office alternative - wps office

Frequently Asked Questions

Why does my Power Automate Excel backup show a file-format mismatch error?

This error occurs when the flow saves invalid data, such as list properties or JSON metadata, instead of the actual binary file content. Excel detects the file as corrupted because the internal structure does not match the expected .xlsx format.

Can changing the file extension fix my corrupted Excel backup?

No. Simply renaming the file extension from .xlsx to .xls and back will not repair the file if the underlying data was saved incorrectly by the workflow. You must fix the workflow to save the correct binary content.

How do I correctly pass file content in a Power Automate flow?

You must use a 'Get file content' action to retrieve the source file's raw binary data. Then, map the 'File Content' dynamic output from that action directly into the corresponding 'File Content' field of your 'Create file' action.

Document & File Issues