microsoft/aspire · warning · OperationCanceledException

{cancellationMessage}

Error message

{cancellationMessage}

What it means

Thrown by WaitForResourceCoreAsync when waiting for a resource condition (running/healthy/etc.) is cancelled. If cancellation came from an OperationCanceledException it is rethrown with an enriched message; otherwise it throws OperationCanceledException directly, indicating the wait ended without the condition ever being met.

Solutions

1. Increase the timeout / cancellation budget around AppHost startup where applicable.
2. Speed up resource startup (pre-pull images, simplify health checks) so waits complete before cancellation.
3. Confirm the waitCondition target is actually attainable (e.g. resource exposes health endpoints for 'healthy').
4. Catch OperationCanceledException in host code to distinguish user-initiated cancellation from genuine startup stalls.

try
{
    await notificationService.WaitForResourceHealthyAsync(resourceName, cancellationToken);
}
catch (OperationCanceledException ex)
{
    logger.LogWarning(ex, "Wait for '{ResourceName}' was cancelled before it became healthy.", resourceName);
}

When it happens

Trigger: WaitForResource/WaitForResourceHealthy/WaitUntil* calls whose CancellationToken fires (Ctrl+C, AppHost shutdown, host-level timeout) while the resource never reached the requested waitCondition; also the fall-through path when the wait completes without a satisfying event.

Common situations: Resource takes longer to start than the surrounding timeout allows (slow image pull, slow health check registration); user aborts `aspire run`; CI test harness cancels AppHost startup.

Understand the failure class

Background: Request timed out: what client-side request timeouts mean across libraries (Request timed out, TIMED_OUT, APITimeoutError) — this error's family across 39 libraries.

Related errors

• {cancellationMessage}
• Graceful budget cannot be negative.
• Resource ' ' failed to wait for dependencies before the…
• A circular lifetime reference was detected for resource
• A global MCP approval policy cannot be combined with custom…

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/9045cd5f5c2f1d78. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Hosting/ApplicationModel/ResourceNotificationService.cs:693

                {
                    continue;
                }

                activity.AddResourceWaitObserved(resourceEvent, waitCondition);

                if (predicate(resourceEvent))
                {
                    activity.AddResourceWaitCompleted(resourceEvent, waitCondition);
                    return resourceEvent;
                }
            }
        }
        catch (OperationCanceledException ex)
        {
            activity.AddResourceWaitCancelled(resourceName, waitCondition);

            var errorMessage = BuildCancellationErrorMessage(cancellationMessage, resourceName);
            throw new OperationCanceledException(errorMessage, ex, ex.CancellationToken);
        }

        throw new OperationCanceledException(BuildCancellationErrorMessage(cancellationMessage, resourceName));
    }
    private readonly object _onResourceUpdatedLock = new();

    /// <summary>
    /// Attempts to retrieve the current state of a resource by resourceId.
    /// </summary>
    /// <remarks>
    /// <para>
    /// A resource id can be either the unique id of the resource or the displayed resource name.
    /// </para>
    /// <para>
    /// Projects, executables and containers typically have a unique id that combines the display name and a unique suffix. For example, a resource named <c>cache</c> could have a resource id of <c>cache-abcdwxyz</c>.
    /// This id is used to uniquely identify the resource in the app host.
    /// </para>
    /// <para>

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