Warning message in async method saying that it lacks await operators

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Am I doing something wrong?

Well, you’re not really doing anything asynchronously. Your ReportExcelAsync method is entirely synchronous, as it doesn’t have any await expressions. So GenerateReportExcel will call ReportExcelAsync, which will run synchronously, and then return a completed task. All you’ve done at the moment is add a small amount of overhead for creating the state machine etc that is used to implement async/await.

It’s not clear why you expected it to actually happen asynchronously, but I suspect it’s a misunderstanding of what await/async actually does. It doesn’t start up new threads for you automatically – it just makes it much easier to create and consume asynchronous APIs.

Now one option is to just want to change ReportExcelAsync into a synchronous method (ReportExcel, returning a string) and create a new task for that in the calling code:

var filePath = await Task.Run(excel.ReportExcel);

However, it’s not clear that this would actually give you much benefit. You’re writing a web app, so it’s not like the response is going to be delivered any faster this way – you’re effectively just shifting the thread the work is done on.

You say:

Since I need it to be done asynchronous

… but give no reasons why it needs to be done asynchronously. What’s wrong with the synchronous approach in this case? Asynchrony is great when it’s appropriate, but I don’t think it is in your case.

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