C#调用上传文件接口返回400

疑问解答
1

已经通过/api/v2.1/dtable/app-upload-link/这个api获取到了upload_link, parent_path和relative_path, 同时已经成功通过postman将文件上传至base, 但在尝试使用.Net HttpClient上传文件时报错，代码如下

string boundary = "----WebKitFormBoundary7MA4YWxkTrZu0gW";
using HttpClient client = new();
using HttpRequestMessage requestMessage = new(HttpMethod.Post, uploadLink);
requestMessage.Headers.Add("Authorization", $"Token {apiToken}");

using MultipartFormDataContent content = new(boundary);
// add file
using FileStream fileStream = File.OpenRead(filePath);
using StreamContent fileContent = new(fileStream);
fileContent.Headers.ContentType = new("application/octet-stream");
fileContent.Headers.ContentDisposition = new("form-data")
{
Name = "\"file\"",
FileName = "\"" + Path.GetFileName(filePath) + "\""
};
content.Add(fileContent);
content.Add(new StringContent(parentPath), "parent_dir");
content.Add(new StringContent(relativePath), "relative_path");
requestMessage.Content = content;

using HttpResponseMessage response = await client.SendAsync(requestMessage);
response.EnsureSuccessStatusCode();
string responseContent = await response.Content.ReadAsStringAsync();

返回为 400 {“error”: "Bad request.
"}

请问是哪一步有问题，我应该如何修改代码