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CA1849: Call async methods when in an async method

  • Article
Property Value
Rule ID CA1849
Title Call async methods when in an async method
Category Performance
Fix is breaking or non-breaking Non-breaking
Enabled by default in .NET 8 No

Cause

All methods where an Async-suffixed equivalent exists will produce this warning when called from a Task-returning method. In addition, calling Task.Wait(), Task<T>.Result, or Task.GetAwaiter().GetResult() will produce this warning.

Rule description

In a method which is already asynchronous, calls to other methods should be to their async versions, where they exist.

How to fix violations

Violation:

Task DoAsync()
{
    file.Read(buffer, 0, 10);
}

Fix:

Await the async version of the method:

async Task DoAsync()
{
    await file.ReadAsync(buffer, 0, 10);
}

When to suppress warnings

It's safe to suppress a warning from this rule in the case where there are two separate code paths for sync and async code, using an if condition. Also if there is a check for whether the Task has resolved, it is safe to use sync methods and properties.

Suppress a warning

If you just want to suppress a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.

#pragma warning disable CA1849
// The code that's violating the rule is on this line.
#pragma warning restore CA1849

To disable the rule for a file, folder, or project, set its severity to none in the configuration file.

[*.{cs,vb}]
dotnet_diagnostic.CA1849.severity = none

For more information, see How to suppress code analysis warnings.

See also