I have been having some trouble lately with OneDrive files not syncing properly, and each time it turns out to be some obscure naming restriction.

Is there a full list somewhere of what filenames are not allowed in OneDrive?

  • Nice self answer. I'd be tempted to try find a title that's going to get more hits from Google, for future searchers. Maybe 'illegal or invalid file names' or something along those lines. – Tetsujin Jun 19 at 16:38
  • @Tetsujin Edited with one attempt; feel free to suggest something else here if you can improve on it. – WBT Jun 19 at 17:36

Microsoft has an article on the topic here. Some highlights:

  • " * : < > ? / \ | characters are not allowed. For some older versions, ~ # % & { }. are also not allowed. (The period in that latter list seems a little alarming!) Less citeable support channels report that dollar signs $ should also be avoided in file names.
  • _vti_ cannot appear anywhere in a file name

  • forms isn't supported as a file name when the folder is at the root level for a library, and sometimes when it is not at the root level for a library. (How was that supposed to be obvious?)

  • You can’t create a folder name in SharePoint Online that begins with a tilde (~) or have any filename starting with ~$.

  • The following names are prohibited: .lock, CON, PRN, AUX, NUL, COM1 - COM9, LPT1 - LPT9, desktop.ini.

  • Active Outlook .PST files should NOT be synced in OneDrive.

  • Symbolic links, junction points, authenticated proxies, and network/mapped drives are not allowed.

  • OneNote notebooks initially created outside of OneDrive cannot be moved into OneDrive.

  • Does it allow Unicode above U+FFFF (e.g. emojis)? Dropbox still doesn't. – grawity Jun 19 at 17:59
  • @grawity I doubt it, and to avoid further complications, will not try. Usability and coverage of unusual characters did not appear to have been considered in the design & programming of this software. – WBT Jun 19 at 19:57

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