OneDrive is a cloud service that allows users around the world to store documents and media “on the cloud.” The cloud broadly refers to the on-demand use of third-party system resources. In OneDrive’s case, Microsoft provides a vast amount of storage space to you; this has many useful applications, but OneDrive still has its quirks, most notably when naming your cloud-stored files and folders.
|OneDrive’s disallowed characters|
This post serves as a resource to aid in naming files for OneDrive, detailing individual characters, phrases, and names to avoid using. You may not see an issue in using invalid characters in OneDrive; you likely don’t know they can cause file and folder sync issues. This issue arises from OneDrive’s use of certain document name characters for background functions. Hence, you cannot enter most of them.
-  What characters cannot be used in OneDrive filenames
-  OneDrive filenames to avoid
-  Filename side-effects in OneDrive
-  Recap & Farewell
What characters cannot be used in OneDrive filenames
Characters you cannot use
Generally, it would be best to avoid any characters listed below in OneDrive filenames; they aid OneDrive (and Windows) in knowing how to behave when you use a file explorer or search for particular files. Due to this, regular files using such characters can (as reported) cause sync issues or otherwise unexpected behavior for the said file.
" Advanced search operator * Advanced search wildcard operator : Indicates start of path within a drive < Unknown > Unknown ? Advanced search operator / Path to folder or file \ Path to folder or file | Unknown
OneDrive filenames to avoid
Reserved filenames you cannot use
As you might expect, if you must avoid particular characters, you must also avoid some names; albeit, names you were unlikely to be using anyway. Funnily enough, attempting to use some blocked filenames triggers the same error a blocked character would.
CON PRN AUX NUL COM0 (COM0 through COM9) LPT0 (LPT0 through LPT9) desktop.ini
In most cases, you can use an invalid filename such as
PRN with minor variations- such as prefixing or suffixing the filename with an underscore. Despite this, there exist filenames that you cannot use in any capacity. The first is: any file containing the
_vti_ string; the second is any file that begins with the
~$ character pair.
Why are these filenames reserved
In recent years Microsoft has been credited for its efforts to keep products backward compatible, most notably with gaming products such as the Xbox One and Xbox 360. However, this is not something new. Back in the DOS era of computing, everything (including external devices and input ports) functioned as files. For instance, if you wished to print a text document, you would just save it to the
PRN file- where your printer would receive and print the file.
Initially, this system persisted through to Windows with Windows 95, which was highly reliant on DOS. However, this may seem irrelevant as Windows NT (a newer Windows system at the time) took a different development path. Despite this, Windows NT was the first to reserve such filenames to maintain backward compatibility with Windows 95- this theme continues in Windows 7 and upward.
Filename side-effects in OneDrive
Trying to rename a file with invalid characters within OneDrive
When you attempt to create or rename an existing file within OneDrive you will find you’re unable to use characters OneDrive does not view as acceptable. If you attempt to do so, you will be met with an error message below your filename stating:
Please enter a name that doesn’t include any of these characters: ” * : < > ? / \ | .OneDrive invalid character error
Trying to rename a file with a reserved name in OneDrive
Unlike invalid characters, entering a reserved filename is not prevented by OneDrive. However, this does not mean your action will take effect. After selecting “Rename” you will be met with an unchanged file and an error stating:
The file or folder name “<PATH TO FILE/FOLDER>” contains invalid characters. Please use a different name. Common invalid characters include the following: # % * : < > ? / |OneDrive reserved filename error
Recap & Farewell
OneDrive is a Microsoft-owned cloud storage platform that allows users to store and share documents and media. The product’s selling feature enables a user’s uploaded content to be accessed once again on other devices using the platform- without consuming their local storage. While OneDrive possesses no detrimental flaws to its functionality, the application does have peculiarities regarding the naming of files. The most notable include several unusable characters, twenty-four mostly unusable filenames, and two completely unusable filenames. One such peculiarity (filenames) is the result of a foundational drawback within Windows 95- persisting solely due to Microsoft’s efforts to keep its products backward compatible with one another.
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