Path encoding and reserved characters

OneDrive supports addressing files and folders using the path of the item in the user's OneDrive. However, because the path contains user specified content which can potentially contain characters that are not URL safe, you should ensure proper encoding of any path segments.

The OneDrive API expects that URLs conform to RFC 3986. The following is a summary of how to properly encode paths for the OneDrive API.

OneDrive reserved characters

The following characters are OneDrive reserved characters, and can't be used in OneDrive folder and file names.

  onedrive-reserved  = "/" / "\" / "*" / "<" / ">" / "?" / ":" / "|"
                     = "/" / "\" / "*" / "<" / ">" / "?" / ":" / "|" / "#" / "%"

Note: Folder names can't end with a period (.).

Note: OneDrive for Business file or folder names cannot begin with a tilde ('~'). See Restrictions and limitations with OneDrive for Business for more information.

URI path characters

When constructing the path segment of a URL for the OneDrive API, the following characters are allowed for path names, based on the URI RFC.

  pchar       = unreserved / pct-encoded / sub-delims / ":" / "@"
  pct-encoded = "%" HEXDIG HEXDIG
  unreserved  = ALPHA / DIGIT / "-" / "." / "_" / "~"
  sub-delims  = "!" / "$" / "&" / "'" / "(" / ")"
              / "*" / "+" / "," / ";" / "="

Item name characters, which are not included in the pchar group, such as # and (space), must be percent encoded.

Encoding characters

The OneDrive API uses standard percent encoding, where invalid characters are encoded with a % and then the UTF-8 character code for the character. For example:

  • " " -> %20
  • "#" -> %23

Common URL encoding mistakes

You can't encode an entire URL in one call, because the encoding rules for each segment of a URL are different. Without proper encoding, the unencoded URL will be ambiguous for which segments contain which content. As such, you need to encode the URL path when building your URL string.

For example, instead of writing this:

string url = url_encode("" + path + ":/children")

Write this:

string url = "" + url_path_encode(path) + ":/children")

However, not all URL encoding libraries respect all the requirements of standard URL path encoding.

.NET / C-Sharp / Visual Basic

The .NET classes for HttpUtility and Uri include various methods for URL encoding. However, none of those methods properly encode all reserved characters for the path component of the URL (including HttpUtility.UrlPathEncode).

Instead of using those methods, you should use UriBuilder to construct a properly escaped URL.

UriBuilder builder = new UriBuilder("");
builder.Path = "/v1.0/drive/root:/Documents/My Files/#nine.docx";
Uri url = builder.Uri;

Objective-C / iOS

For Objective-C, iOS and Mac OS X development, use the stringByAddingPercentEncodingWithAllowedCharacters method and [NSCharacterSet URLPathAllowedCharacterSet] to properly encode the path component of the URL.

NSString *root = @"";
NSString *path = @"Documents/My Files/#nine.docx";
NSString *encPath = [path stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLPathAllowedCharacterSet]];
NSURL *url = [[NSURL alloc] initWithString:[root stringByAppendingString:encPath]];


Use the Uri.Builder class to construct a properly encoded URL.

Uri.Builder builder = new Uri.Builder();
  appendPath("My Files").
String url =;


Use escape() in JavaScript to properly encode a path component.

var root = "";
var path = "/Documents/My Files/#nine.docx";
var url = root + escape(path);


Here is an example of a OneDrive user (Ryan) with the following folder hierarchy:

    \Ryan's Files
        \doc (1).docx

To address each of Ryan's files, you use percent encoding, as follows:

Path Encoded URL for path
\Ryan's Files /root:/Ryan's%20Files
\...\doc (1).docx /root:/Ryan's%20Files/doc%20(1).docx
\...\estimate%.docx /root:/Ryan's%20Files/estimate%25s.docx
\Break#Out /root:/Break%23Out
\...\saved_game[1].bin /root:/Break%23Out/saved_game[1].bin