{"record":{"id":"c7d7ce79f78bf064","repo":"microsoft/aspire","slug":"the-launchconfigurationtype-launch-configuration-producer","errorCode":null,"errorMessage":"The \"{launchConfigurationType}\" launch configuration producer for resource '{resourceName}' returned null. The producer owns the complete launch configuration, so it must always return one.","messagePattern":"The \"(.+?)\" launch configuration producer for resource '(.+?)' returned null\\. The producer owns the complete launch configuration, so it must always return one\\.","errorType":"exception","errorClass":"InvalidOperationException","httpStatus":null,"severity":"error","filePath":"src/Aspire.Hosting/SupportsDebuggingAnnotation.cs","lineNumber":66,"sourceCode":"    internal Func<LaunchConfigurationCallbackContext, Task<object>> LaunchConfigurationProducer { get; }\n\n    internal static SupportsDebuggingAnnotation Create<T>(\n        string resourceName,\n        string launchConfigurationType,\n        Func<LaunchConfigurationCallbackContext, Task<T>> launchConfigurationProducer)\n    {\n        return new SupportsDebuggingAnnotation(\n            launchConfigurationType,\n            // The suppression is safe because ProduceAsync throws rather than returning null; the\n            // compiler cannot see that because T is unconstrained and so may be a nullable type.\n            async context => (await ProduceAsync(context).ConfigureAwait(false))!);\n\n        async Task<T> ProduceAsync(LaunchConfigurationCallbackContext context)\n        {\n            var launchConfiguration = await launchConfigurationProducer(context).ConfigureAwait(false);\n            if (launchConfiguration is null)\n            {\n                throw new InvalidOperationException(\n                    $\"The \\\"{launchConfigurationType}\\\" launch configuration producer for resource '{resourceName}' returned null. \" +\n                    $\"The producer owns the complete launch configuration, so it must always return one.\");\n            }\n\n            return launchConfiguration;\n        }\n    }\n}\n","sourceCodeStart":48,"sourceCodeEnd":75,"githubUrl":"https://github.com/microsoft/aspire/blob/25830f84bd145686607ad00c057b3f84e2e51d43/src/Aspire.Hosting/SupportsDebuggingAnnotation.cs#L48-L75","documentation":"A launch configuration producer registered via debug support must always yield a non-null launch configuration because it fully owns constructing it. SupportsDebuggingAnnotation.Create wraps the producer and throws this InvalidOperationException if the awaited producer returns null. This catches buggy producers (e.g. a method with a nullable return that falls through to null) before an incomplete launch configuration is used.","triggerScenarios":"A launchConfigurationProducer delegate whose awaited result is null — e.g. an async method returning null on a code path, a context lookup that misses, or a producer written as a lambda returning a null value.","commonSituations":"Producers that look up configurations by mode and return null for unknown modes, refactors that made a producer return nullable types, or factories returning null on error instead of throwing.","solutions":["Fix the producer to always return a constructed launch configuration object (throw on unrecoverable paths instead of returning null)","Return an empty/default launch configuration rather than null for unknown launch modes","Log and inspect the producer's code paths that can return null"],"exampleFix":"// before\nasync Task<LaunchConfiguration> ProduceAsync(LaunchConfigurationCallbackContext ctx) =>\n    ctx.LaunchMode == \"Debug\" ? new LaunchConfiguration() : null;\n// after\nasync Task<LaunchConfiguration> ProduceAsync(LaunchConfigurationCallbackContext ctx) =>\n    ctx.LaunchMode == \"Debug\"\n        ? new LaunchConfiguration()\n        : throw new InvalidOperationException($\"Unsupported launch mode '{ctx.LaunchMode}'.\");","handlingStrategy":"type-guard","validationCode":"object EnsureNotNull(LaunchConfiguration? config) =>\n    config ?? throw new InvalidOperationException(\"Producer returned null; return a LaunchConfiguration instance.\");","typeGuard":"if (producerResult is null) throw new InvalidOperationException(\"Launch configuration producer must not return null.\");","tryCatchPattern":"try { await annotation.ProduceAsync(context); }\ncatch (InvalidOperationException ex) when (ex.Message.Contains(\"launch configuration producer\")) { logger.LogError(ex, \"Producer for {Resource} returned null\", context.ResourceName); }","preventionTips":["Return non-nullable LaunchConfiguration from producers so the compiler flags null paths","Throw on unsupported launch modes instead of returning null","Test producers for every launch mode the AppHost uses"],"tags":["aspire","debugging","null","launch-configuration"],"backgroundTag":"null-argument","analyzedSha":"25830f84bd145686607ad00c057b3f84e2e51d43","analyzedAt":"2026-09-16T11:10:06.193Z","contentChangedAt":"2026-09-16T11:10:06.193Z","schemaVersion":2},"datasetVersion":"2026-09-21T04:17:39.646Z"}