microsoft/aspire · error · InvalidOperationException

App Service context not found for resource

Error message

App Service context not found for resource {resource.Name}.

What it means

AzureAppServiceEnvironmentContext keeps a per-resource map of AzureAppServiceWebsiteContext instances created during App Service infrastructure generation. GetAppServiceContext throws this error when asked for a resource that never had a context created — meaning the resource is not registered as an App Service website in this environment.

Solutions

Only call GetAppServiceContext for resources configured with PublishAsAzureAppServiceWebsite.
Verify the exact IResource instance passed matches the one registered (not a copy or different builder's resource).
Create the context via the environment context's creation path (CreateAppServiceAsync / context map population) before fetching it.
Check for the AzureAppServiceWebsiteCustomizationAnnotation before calling.

Example fix

// before
var ctx = envContext.GetAppServiceContext(anyResource);
// after
if (anyResource.HasAnnotationOfType<AzureAppServiceWebsiteCustomizationAnnotation>())
{
    var ctx = envContext.GetAppServiceContext(anyResource);
}

Defensive patterns

Strategy: validation

Validate before calling

if (!resource.HasAnnotationOfType<AzureAppServiceWebsiteCustomizationAnnotation>()) throw new InvalidOperationException("Resource is not an App Service website; no context will exist.");

Type guard

bool HasAppServiceContext(IResource r) => r.HasAnnotationOfType<AzureAppServiceWebsiteCustomizationAnnotation>();

Try / catch

try { var ctx = envContext.GetAppServiceContext(resource); } catch (InvalidOperationException ex) { logger.LogWarning(ex, "No App Service context for {Resource}", resource.Name); }

Prevention

Only fetch contexts for resources processed by the App Service pipeline.
Pass the same IResource instance that was registered, not a clone.
Register contexts before any consumer queries them in custom pipeline steps.

When it happens

Trigger: Calling GetAppServiceContext for an IResource that was never processed by CreateAppServiceAsync / the App Service compute callbacks — e.g. a resource without the App Service customization annotation, a plain container without PublishAsAzureAppServiceWebsite, or a resource added to the model after contexts were built.

Common situations: Custom publishing pipeline steps that query contexts for arbitrary model resources; resources added via polyglot/other providers that bypass App Service registration; referencing a different resource instance than the one registered (dictionary is keyed by IResource identity).

Understand the failure class

Background: Record Not Found Errors: "not found", RecordNotFound, and "was not found" — what they mean and how to fix them — this error's family across 28 libraries.

Related errors

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/f48008344f4ea1aa. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Hosting.Azure.AppService/AzureAppServiceEnvironmentContext.cs:66

        _hasLoggedHttpsUpgrade = true;

        var details = string.Join(", ", _upgradedEndpoints.Select(x =>
            x.EndpointNames.Length == 1
                ? $"{x.ResourceName}:{x.EndpointNames[0]}"
                : $"{x.ResourceName}:{{{string.Join(", ", x.EndpointNames)}}}"));

        Logger.LogInformation(
            "HTTP endpoints will use HTTPS (port 443) in Azure App Service: {Details}. " +
            "To opt out, use .WithHttpsUpgrade(false) on the app service environment.",
            details);
    }

    public AzureAppServiceWebsiteContext GetAppServiceContext(IResource resource)
    {
        if (!_appServices.TryGetValue(resource, out var context))
        {
            throw new InvalidOperationException($"App Service context not found for resource {resource.Name}.");
        }

        return context;
    }

    public async Task<AzureBicepResource> CreateAppServiceAsync(IResource resource, AzureProvisioningOptions provisioningOptions, CancellationToken cancellationToken)
    {
        if (!_appServices.TryGetValue(resource, out var context))
        {
            _appServices[resource] = context = new AzureAppServiceWebsiteContext(resource, this);
            await context.ProcessAsync(cancellationToken).ConfigureAwait(false);
        }

        var provisioningResource = new AzureAppServiceWebSiteResource(resource.Name + "-website", context.BuildWebSite, resource)
        {
            ProvisioningBuildOptions = provisioningOptions.ProvisioningBuildOptions
        };

View on GitHub (pinned to 25830f84bd)