异步方法签名错误。 必须返回void，Task或Task <T>

Question

I have an async method.

private static async Task InsertConnectionStatusIntoAzureDatabaseAsync(Device device)
{
   ...
}

I call it using

await InsertConnectionStatusIntoAzureDatabaseAsync(device).ConfigureAwait(false);

Visual studio will not build saying that an async method must return void, Task or Task<T>

It also red squiggles the line InsertConnectionStatusIntoAzureDatabaseAsync(device).ConfigureAwait(false); saying :

Task does not contain a definition for ConfigureAwait()

The usings at the top of the file are

using System.Threading.Tasks;
using System.Threading;

The .net framework it targets is 4.6.1

Answer 1

You almost certainly have another class in your project called Task which is conflicting with the .Net Framework version. You can check this by going to the definition of the Task type and see where it leads you. So either rename your version to something distinct (probably the best option) or use the full namespace:

private static async System.Threading.Tasks.Task InsertConnectionStatusIntoAzureDatabaseAsync()
{
    //snip
}

Answer 2

You can as well use namespace alias and use that in your method signatire like

using task = System.Threading.Tasks;

    private static async task.Task InsertConnectionStatusIntoAzureDatabaseAsync(Device device)
    {
       ...
    }