I'm currently running into an issue with creating a folder titled "large_files"

When using the Web UI in OneDrive for Business I've created the following folder /personal/tenant_awbrazier_onmicrosoft_com/Documents/large_files

This allows you to create the folder but does not appear in the UI, when I go to create it again it says it exists.

When I try the following using the REST API, I can create it, returns a UniqueID, but when I try and perform any other operations it says the folder does not exist. I have a unique id returned from the API so surely it should exist?

Are there any other reserved folder names that should not be used? I know forms is one, in the route ie Documents/Forms and you can't use ~FolderName

Has anyone come across this before is this a bug?

The same happens with team sites, when creating in Shared Documents

2 Answers 2


The problem with the folder name "large_files" is that it ends with the string "_files". This is a reserved name for SharePoint Online. Scroll down here http://support.microsoft.com/kb/905231 and you will see that extension listed, amongst a number of others.

For a list of reserved/blocked characters in SharePoint Online check this link https://support.office.com/en-gb/article/Invalid-characters-in-file-or-folder-names-or-invalid-file-types-in-OneDrive-for-Business-64883a5d-228e-48f5-b3d2-eb39e07630fa and this one for blocked file extensions https://support.office.com/en-gb/article/Types-of-files-that-cannot-be-added-to-a-list-or-library-30be234d-e551-4c2a-8de8-f8546ffbf5b3

  • Thanks, it appears it does let you create them still which is very odd, going on web ui and the rest.
    – Webfort
    Commented Feb 3, 2015 at 16:35

See in image and also referenced link Reference:https://support.office.com/en-us/article/Invalid-file-names-and-file-types-in-OneDrive-OneDrive-for-Business-and-SharePoint-64883a5d-228e-48f5-b3d2-eb39e07630fa Image

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