Azure函数未给出有效的Base-64字符串错误

我有一个带有CosmosDB输出绑定的http触发器和一个最简单的函数,如下所示。

 public static class AddRequest
{
    [FunctionName("AddRequest")]
    public static async Task<IActionResult> Run(
        [HttpTrigger(AuthorizationLevel.Function, "post", Route = null)] HttpRequest req,
        ILogger log, [CosmosDB(
            databaseName: "haveThatDB",
            collectionName: "Requests",
            ConnectionStringSetting = "MongoDBEndPoint",CreateIfNotExists =true)] IAsyncCollector<Request> requestOutput
       )

    {
       string jsonContent = await req.ReadAsStringAsync();
        dynamic data = JsonConvert.DeserializeObject(jsonContent);

        await requestOutput.AddAsync(data);

        return req != null
           ? (ActionResult)new OkObjectResult($"Hello, ras")
           : new BadRequestObjectResult("Please pass a name on the query string or in the request body");
    }
}

当我执行时,我得到一个错误

异常绑定参数'requestOutput'。System.Private.CoreLib:输入不是有效的Base-64字符串,因为它包含非Base 64字符、两个以上的填充字符或填充字符中的非法字符

我正在使用azure函数的V2。

local.settings内容如下

{ “IsEncrypted”:错误, “AzureWebJobsStorage”:“UseDevelopmentStorage=true”, “函数\u工作者\u运行时”:“dotnet”, “MongoDBEndPoint”:“AccountEndpoint”= https://abc.documents.azure.com:10255;AccountKey=xxxxxxxxxxxxyyyyyyyyzzzzzzz “MongoDBName”:“haveThatDB” } }