microsoft/aspire · error · InvalidOperationException

Cannot create a Microsoft Foundry project connection to an…

Error message

Cannot create a Microsoft Foundry project connection to an emulator Storage account.

What it means

Foundry project connections require a real Azure Storage account endpoint. AddConnection for Storage throws this InvalidOperationException when the supplied AzureStorageResource is running as the local emulator (Azurite), since Foundry cannot access it.

Solutions

1. Remove RunAsEmulator() from the Storage resource so a real account is provisioned.
2. Conditionally add the connection only when the storage resource is not emulated.
3. Declare a separate real Storage resource dedicated to the Foundry connection.

Example fix

// before
var storage = builder.AddAzureStorage("storage").RunAsEmulator();
project.AddConnection(storage); // throws

// after
var storage = builder.AddAzureStorage("storage");
project.AddConnection(storage);

if (!storage.IsEmulator())
    project.AddConnection(storage);

try { project.AddConnection(storage); } catch (InvalidOperationException ex) when (ex.Message.Contains("emulator Storage")) { /* skip or provision real Storage */ }

When it happens

Trigger: Calling foundryProject.AddConnection(storage) where the AzureStorageResource builder had RunAsEmulator() applied (storage.IsEmulator() returns true).

Common situations: Local dev setups using Azurite while also registering a Foundry blob connection; templates that default resources to emulator mode for fast startup.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Cannot create a Microsoft Foundry project connection to an…
• Cannot create a Microsoft Foundry project connection to an…
• Cannot create a Microsoft Foundry project connection to an…
• BlobServiceClient is not initialized.
• Emulator currently does not support data lake.

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/bfaf485121bbc6f6. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Hosting.Foundry/Project/ConnectionBuilderExtensions.cs:137

        IResourceBuilder<AzureCosmosDBResource> db)
    {
        return builder.AddConnection(db.Resource);
    }

    /// <summary>
    /// Adds an Azure Storage account to a project as a connection.
    /// </summary>
    /// <returns></returns>
    [AspireExportIgnore(Reason = "Raw AzureStorageResource parameters are not ATS-compatible. Use the resource-builder overload instead.")]
    public static IResourceBuilder<AzureCognitiveServicesProjectConnectionResource> AddConnection(
        this IResourceBuilder<AzureCognitiveServicesProjectResource> builder,
        AzureStorageResource storage)
    {
        ArgumentNullException.ThrowIfNull(builder);
        ArgumentNullException.ThrowIfNull(storage);
        if (storage.IsEmulator())
        {
            throw new InvalidOperationException("Cannot create a Microsoft Foundry project connection to an emulator Storage account.");
        }
        return builder.AddConnection($"connection-{Guid.NewGuid():N}", (infra) => new AadAuthTypeConnectionProperties()
        {
            Category = CognitiveServicesConnectionCategory.AzureBlob,
            Target = storage.BlobEndpoint.AsProvisioningParameter(infra),
            IsSharedToAll = true,
            Metadata =
            {
                { "ApiType", "Azure" },
                { "ResourceId", storage.Id.AsProvisioningParameter(infra) }
            }
        });
    }

    /// <summary>
    /// Adds an Azure Storage account to a project as a connection.
    /// </summary>
    [AspireExport("addStorageConnection")]

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