C#调用Power BI REST API报错：Authorization标头不支持多值

错误信息 #

Cannot add value because header 'Authorization' does not support multiple values.

复现代码 #

public static async Task createNewWorkspace(string workspaceName)
{
    bearer = "";
    workspaceName = "TESTING";
    //Create Workspace 
    var url = "https://api.powerbi.com/v1.0/myorg/groups?workspaceV2=True";
    var content = new StringContent("{\"name\": \"" + workspaceName + "\"}", Encoding.UTF8, "application/json");

    if (client.DefaultRequestHeaders.Contains("Authorization"))
    {
        client.DefaultRequestHeaders.Remove("Authorization");
    }
   client.DefaultRequestHeaders.Add("Authorization", "Bearer " + bearer);
   var response = await client.PostAsync(url, content);
}

执行var response = await client.PostAsync(url, content);行时触发上述错误。

已尝试的排查方法 #

• 添加判断并移除Authorization标头（无效）
• 尝试多种授权写法：

// 写法1
client.DefaultRequestHeaders.TryAddWithoutValidation("Authorization", "Bearer" + bearer);

// 写法2
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", bearer);

// 写法3
client.DefaultRequestHeaders.Remove("Authorization");
client.DefaultRequestHeaders.Add("Authorization", "Bearer " + bearer);

• 参考过相关技术论坛解决方案

补充信息 #

1. 本人是C#新手，这是第一个项目
2. 直接调用createNewWorkspace方法可正常运行，但从遍历SQL查询结果的方法中调用时会触发错误
3. 使用的HttpClient为静态只读实例：

static readonly HttpClient client = new HttpClient();

4. 更新代码后，工作区能创建但仍报FORBIDDEN错误，且总是先创建成功再触发错误

内容的提问来源于stack exchange，提问作者NutellaKing