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Learn how to solve the 'Cannot await 'void'' error in your C# async methods by replacing Thread.Sleep with Task.Delay for better performance and functionality.
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This video is based on the question https://stackoverflow.com/q/64629190/ asked by the user 'Axqua' ( https://stackoverflow.com/u/14382870/ ) and on the answer https://stackoverflow.com/a/64629363/ provided by the user 'sobby01' ( https://stackoverflow.com/u/358136/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Cannot await 'void' Error in C#

Working with asynchronous programming in C# can often lead to frustrating errors, one of the most common being the dreaded message: Cannot await 'void'. This error typically arises when a method that returns void is used with the await keyword, which is meant for methods that return a Task or Task<TResult>. In this guide, we’ll take a closer look at this issue through a practical example and show you how to resolve it effectively.

The Problem: Understanding the Code

Consider the following snippet from a C# application:

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In this example, the line await Thread.Sleep(3000); is causing the error message because Thread.Sleep is a blocking call and does not return a Task, which means it cannot be awaited. This leads to a situation where the compiler cannot allow you to use await on a method that returns void.

The Solution: Replace Thread.Sleep with Task.Delay

The effective solution involves using Task.Delay instead of Thread.Sleep. Here's the corrected line of code:

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Why Replace Thread.Sleep with Task.Delay?

Non-blocking Behavior:
Thread.Sleep blocks the current thread for the specified duration, halting all execution on that thread. This can lead to unresponsive UI components or other issues in applications that rely on smooth user experiences.

Asynchronous Handling:
In an asynchronous method, you want to allow other operations to continue while waiting. Task.Delay provides a way to pause the execution logically without freezing the entire thread.

Implementation of the Correction

After making the change, your secondmult_Click method will look like this:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

In conclusion, when working with asynchronous programming in C# , always ensure that you replace blocking calls like Thread.Sleep with non-blocking alternatives like Task.Delay. This practice not only prevents errors such as Cannot await 'void' but also helps maintain a responsive and efficient application workflow.

Now, whenever you encounter a similar situation in your C# code, you'll know precisely how to solve it! Happy coding!