If you want to await on a delegate, it has to be of type Func<Task> or Func<Task<T>>. An Action is equivalent into a void Action() named method. You can’t await on void, yet you can await Task Func() or Task<T> Func:
public async Task ExecuteAsync(Func<Task> func)
{
try
{
await func();
}
finally
{
}
}
If this can’t be done, it means that internally the method isn’t truly asynchronous, and what you actually want to do is execute the synchronous delegate on a thread-pool thread, which is a different matter, and isn’t really executing something asynchronously. In that case, wrapping the call with Task.Run will suffice.