使用下面的 C# 代码用 refresh token 刷新 access token

var httpClient = _httpClientFactory.CreateClient();

var parameters = new FormUrlEncodedContent(new Dictionary<string, string>
{
    ["client_id"] = _apiOptions.ClientId,
    ["client_secret"] = _apiOptions.ClientSecret,
    ["grant_type"] = "refresh_token",
    ["refresh_token"] = _memoryCache.Get<string>(nameof(TokenResponse.RefreshToken))
});

var response = await httpClient.PostAsync($"{_apiOptions.OauthUrl}/connect/token", parameters);

错误响应是

{"error":"invalid_request"}

请问如何解决？