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Error Opening Excel Workbook Created by Power Automate

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Posted on by Phineas

5,325 Super User 2025 Season 2

I am getting a file extension error when I try to open an Excel workbook created by flow.

There is Excel Workbook1, that is sent to an email inbox, either several times a day or several times a week.

There is Flow1 (created by another), that moves a copy / overwrites Workbook1 to SharePoint Folder1. There is a predetermined file name (the file name is always the same).

When I try to open Workbook1, created by Flow1, I get the following error.

What am I missing? How do I correct this error?

The flow (that moves the workbook from the inbox to the SP folder)

The folder (with file) -
The SharePoint folder where Flow1 moves/copies inbox Workbook1.

The error -
The workbook couldn't be opened because the file format may not be matching
with the file extension.

Categories:

Building flows

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trice602 15,404 Super User 2025 Season 2 on at

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Hi @Phineas ,

What is the file attachment that is being captured by email?

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Phineas 5,325 Super User 2025 Season 2 on at

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I'm not sure, but I've always assumed it is some form of excel file; Presumably xlsx.

All versions I have opened and viewed, outside the influence of modifications by flow, have been xlsx.

Another thought - should the action in the flow be 'Update file' or 'Create file'?

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trice602 15,404 Super User 2025 Season 2 on at

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Hi @Phineas ,

Goes without saying, it makes a huge difference! Here's what to do: go to the last failed run, or the run that you got that error message, and look at the trigger output and see what file you are trying to process. More likely that not, the file is not an excel file OR an .xlsx file. Please check and then mark as a solution if I am correct. Then I can show you how to only process .xlsx files with a conditional action.

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Phineas 5,325 Super User 2025 Season 2 on at

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Well, here is a fine twist...

The flow didn't fail.

The flow completed successfully; The error occurs when trying to open the newly created/overwritten workbook.

The file, as created/overwritten in the folder by the successfully completed flow.

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trice602 15,404 Super User 2025 Season 2 on at

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Hi @Phineas ,

Understood. When you review the trigger outputs, what is the file attachment getting processed?

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Phineas 5,325 Super User 2025 Season 2 on at

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This is the trigger info -

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trice602 15,404 Super User 2025 Season 2 on at

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Hi @Phineas ,

You have to look at the trigger OUTPUT, not the trigger itself. In your run that you cannot open the attachment, open the successful flow, then under Output, click on 'Click to download':

In the output, review the file attachment and validate the attachment type:

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Phineas 5,325 Super User 2025 Season 2 on at

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In your example you have 'Yes' in the include attachments.

In my process only a specific file/attachment is desired, not all files/attachments.

What should my 'Include Attachments' be set to?

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Phineas 5,325 Super User 2025 Season 2 on at

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Here ya go.

An aside...does the name (called out by my arrow) matter? As it doesn't match the name in the folder.
Though the error isn't about he name but about the file type.

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trice602 15,404 Super User 2025 Season 2 on at

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Hi @Phineas ,

Thanks for sharing. The file type is correct so please turn on include attachments and run again.

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