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

Anonymous

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.

Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.

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Answer accepted by question author

Anonymous

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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58 additional answers

Anonymous

2024-01-25T20:03:35+00:00

Update, had her try it on another computer and she was able to do so with no errors. It is specific to her account on THAT computer as far as we can tell.

We also tried it with a brand-new blank workbook and got the error message.
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Anonymous

2024-01-26T05:15:14+00:00

You may try deleting this folder to reset Excel (Close all the Excel first). It will recreate automatically.

Computer\HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Excel
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Anonymous

2024-01-26T15:50:27+00:00

You may try deleting this folder to reset Excel (Close all the Excel first). It will recreate automatically.

Computer\HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Excel

No luck, this did not resolve the issue
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Anonymous

2024-01-26T16:01:30+00:00

I have no other idea on it. You may try creating a support ticket to Microsoft.

Please contact your admin/IT department create a support ticket via Microsoft 365 Admin Center> Support> New service request. Support team there will have the correct channel and resources to help you investigate more and find what exactly the reason has caused this situation.
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