I want to upload a file to a sub folder of a document Library in Sharepoint Online.

I have an error when posting the file: "URL is not web relative". I don't understand because I can read the content of the sub folder with a GET Request.

My file full path exists, I can read it and transform it to a ByteArrayContent.

My code:

 // Upload
                using (HttpClient client = new HttpClient())
                    // Access Token with Bearer
                    client.DefaultRequestHeaders.TryAddWithoutValidation("Authorization", $"Bearer { accessToken }");

                    client.DefaultRequestHeaders.TryAddWithoutValidation("Accept", "application/json;odata=verbose");

                    client.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json;odata=verbose");

                        // Ok, I can get the result from this url
                        string uriGet = $"{ _baseUri }/_api/web/getFolderByServerRelativeUrl('Shared Documents/MyFolder')";

                        var resultGet = await client.GetAsync(uriGet);
                        var stringResultGet = await resultGet.Content.ReadAsStringAsync();

                        // But, posting a file isn't working on the same folder
                        string uri = $"{ _baseUri }/_api/web/getFolderByServerRelativeUrl('Shared Documents/MyFolder')/files/add(url='{ fileFullPath }', overwrite=true)";

                        var bytes = System.IO.File.ReadAllBytes(fileFullPath);

                        ByteArrayContent byteArrayContent = new ByteArrayContent(bytes);

                        var result = await client.PostAsync(uri, byteArrayContent);

                        var stringResult = await result.Content.ReadAsStringAsync();
                    catch (Exception ex)


Thanks for your help !

  • I don't have the rep here to comment... sorry Can you explain how you can specify a path when you can only specify a file name? Is that only possible by changing the current directory?
    – Siete
    Nov 1, 2022 at 15:19
  • You can ask a new question using Ask Question. Provide link to this post as it provides context for your question. Nov 1, 2022 at 15:23

1 Answer 1


You shouldn't specify the complete URL of the file in here: .../files/add(url='{ fileFullPath }', overwrite=true)";

Just specify the filename within the folder. ex.: document.docx.

  • Thank you very much, it solved my issue
    – GwenGuts
    Aug 24, 2020 at 7:13

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