Excel HTTP Error 400. The size of the request headers is too long

Anonymous
2024-01-25T17:23:24+00:00

Good afternoon,

Today I was helping a user, Alice, change a picture in the header of an excel workbook. When Alice clicks the "picture" button in the ribbon under the "Header and footer" tab, instead of showing the dialog to pick a file to insert, the window that pops up says "HTTP Error 400. The size of the request headers is too long" with no other information.

Notably, if Bob, another user with an apparently identical account and user profile, tries to follow the same steps on the same computer as Alice, Bob is able to do so without receiving the error message.

We have tried the following:

Reinstall office365

Sign out of user account and back in

Split the document into smaller documents in case it was a file size issue

Running the repair tool for office365

Thank you!

Edit:

Good morning! I am happy to say we found a solution! Unfortunately it was to reinstall Windows.

Microsoft 365 and Office | Excel | For business | Windows

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Anonymous
2024-02-01T11:11:15+00:00

Good afternoon,

Today I was helping a user, Alice, change a picture in the header of an excel workbook. When Alice clicks the "picture" button in the ribbon under the "Header and footer" tab, instead of showing the dialog to pick a file to insert, the window that pops up says "HTTP Error 400. The size of the request headers is too long" with no other information.

Notably, if Bob, another user with an apparently identical account and user profile, tries to follow the same steps on the same computer as Alice, Bob is able to do so without receiving the error message.

We have tried the following:

Reinstall office365

Sign out of user account and back in

Split the document into smaller documents in case it was a file size issue

Running the repair tool for office365

Thank you!

the following solution is also possible:

file - account - settings management - turn off optional online functions and done

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  1. Anonymous
    2024-04-26T19:55:30+00:00

    I had the same issue. It's a simple fix that I just stumbled across.

    File> Options> Advanced> General> Web Options> Files>

    Just uncheck "Use long file names whenever possible"

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  2. Anonymous
    2024-04-29T09:22:32+00:00

    Thanks, but this still won't work for us. I've tried all suggestions from multiple forums, apart from reinstalling Windows 11; which seems a bit extreme!

    I have our IT support looking into this as well and they have been getting stumped also, if we find a resolve then I'll post it to this thread.

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  3. Anonymous
    2024-04-29T12:34:56+00:00

    I has just worked! Thank you so much. I have switched the Internet connection off and tried to insert the picture in the header. When the pop-up window appeared, I clicked in Work Offline. I have managed to pick the picture from the folders I had synched in my machine.

    I have since switched the Internet connection back on and all looks fine. The document is now synched to the cloud with the correct picture in the header.

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  4. Anonymous
    2024-04-29T16:45:45+00:00

    Interestingly, if you switch "Use long file names whenever possible' back on it continues to work!

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