CA2261: Do not use ConfigureAwaitOptions.SuppressThrowing with Task<TResult>

Property	Value
Rule ID	CA2261
Title	Do not use ConfigureAwaitOptions.SuppressThrowing with Task<TResult>
Category	Usage
Fix is breaking or non-breaking	Non-breaking
Enabled by default in .NET 9	As warning

Cause

A value of ConfigureAwaitOptions.SuppressThrowing is passed to Task<TResult>.ConfigureAwait(ConfigureAwaitOptions).

Rule description

The ConfigureAwaitOptions.SuppressThrowing option isn't supported by the generic Task<TResult>, since that might lead to returning an invalid TResult. This rule flags the use of SuppressThrowing with Task<TResult> to surface the error at build time rather than run time.

How to fix violations

Cast the Task<TResult> to a non-generic Task before calling ConfigureAwait(ConfigureAwaitOptions).

Example

The following code snippet shows a violation of CA2261:

Task<int> t = new Task<int>(() => 1);
t.ConfigureAwait(ConfigureAwaitOptions.SuppressThrowing);

The following code snippet shows the fix:

Task<int> t = new Task<int>(() => 1);
((Task)t).ConfigureAwait(ConfigureAwaitOptions.SuppressThrowing);

When to suppress errors

You shouldn't suppress warnings from this rule. If the task is faulted or canceled, TResult will be invalid and cause run-time errors.