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Power Automate Flow Suddenly Failing with "Invalid File Name" for Dynamic OneDrive Filenames

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Posted on by AA-20060055-0

My Power Automate flow has been working for about two months with 150+ successful submissions using dynamic filenames in the format JP-yyyyMMdd-HHmmss. On 19 Jun 2026, it suddenly started failing in the OneDrive for Business Create File action with "Invalid file name", despite no changes to the flow, file naming logic, template, folder path, or licensing. The Compose and Word Template actions complete successfully, the generated JP number is valid, storage is available, and no duplicate files exist. A static filename such as test.docx works, but the dynamic filename that previously worked now fails. Has anyone experienced a recent issue with OneDrive Create File or dynamic filenames in Power Automate?

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chiaraalina 2,425 Super User 2026 Season 1 on at

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Hi

Can you share the exact expression or dynamic content you are using in the OneDrive Create file -> File Name field?

The post shows the intended format JP-yyyyMMdd-HHmmss, but we need to see the actual Power Automate expression, for example whether it is something like: concat('JP-', formatDateTime(utcNow(),'yyyyMMdd-HHmmss'), '.docx')

Also, please share the Show raw inputs from the failed Create file action, especially the resolved name value.

Thanks!

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AA-20060055-0 8 on at

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Hi chiaraalina,

Thank you for your response.

I have attached screenshots of both the File Name configuration and the raw inputs from the failed Create File action.

One thing I noticed is that the raw input contains:

"name": "JP-20260622-131951\n.docx" (I dont know how to remove it if you suggest to do so)

However, I also found successful runs from earlier that contain the same pattern with "\n", which makes me unsure whether it is the actual cause of the failure.

Interestingly, static filenames such as "test.docx" and "JP-20260623.docx" work without a
ny issues, while the dynamically generated filename fails.

I would appreciate your thoughts after reviewing the screenshots.

Thank you.

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Ellis Karim 12,163 Super User 2026 Season 1 on at

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It seems that the file name P-20260622-131951\n.docx has a newline character (known as Line Feed) inserted, so it really looks like this:

P-20260622-131951 .docx

The newline character (\n) can't be used in OneDrive filenames.

You can use a replace function to remove this character:

replace( variables('FileName'), decodeUriComponent('%0A'), '' )

Character Name Encoded

\n Line Feed (LF) %0A

\r Carriage Return (CR) %0D

\r\n Windows newline %0D%0A

Ellis Karim
elliskarim.com | LinkedIn | Bluesky
If this solved your issue, please mark it as ✅ Accepted Answer. If it helped, feel free to give it a 🩷 Like!

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AA-20060055-0 8 on at

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Hi Ellis Karim,

Thank you very much for your help and for taking the time to review my issue. Your suggestion was exactly what solved the problem. The filename contained hidden newline characters, and using the replace() function to remove %0A and %0D before passing the value to the OneDrive Create File action fixed the issue completely.

Thank you again for your support

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