Logic App Standard扩展包不支持MSI连接存储账户排查咨询

The error Microsoft.WindowsAzure.Storage: Value cannot be null. (Parameter 'connectionString') occurs because your 1.x extension bundle doesn't support MSI authentication for the core AzureWebJobsStorage connection. Here are step-by-step troubleshooting directions:

1. Upgrade Extension Bundle to 2.x or Later #

The 1.x Microsoft.Azure.Functions.ExtensionBundle.Workflows bundle doesn't support MSI for AzureWebJobsStorage. Update your host.json to use a 2.x version range:

{
  "version": "2.0",
  "logging": {
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": true,
        "excludedTypes": "Request"
      }
    }
  },
  "extensionBundle": {
    "id": "Microsoft.Azure.Functions.ExtensionBundle.Workflows",
    "version": "[2.*, 3.0.0)"
  }
}

• Ensure your Function App uses .NET 6 runtime (required for 2.x bundles): Go to Azure Portal > Function App > Configuration > General settings > Runtime version, set to ~4 (maps to .NET 6).

2. Confirm MSI Permissions on Storage Account #

Your Logic App's managed identity needs sufficient permissions to access the storage account:

• Assign either Storage Account Contributor or Storage Blob Data Contributor role to the identity (system or user-assigned).
• Navigate to your Storage Account > Access control (IAM) > Add role assignment > Select the role > Search for your Logic App's identity and assign it.

3. Configure Correct Application Settings #

Use the right app setting format for MSI authentication:

• System-assigned MSI: Keep AzureWebJobsStorage__accountName=your-storage-account-name (this works with 2.x bundles).
• User-assigned MSI: Add an additional setting: AzureWebJobsStorage__clientId=your-msi-client-id.
• Remove any existing AzureWebJobsStorage setting that contains a full connection string (it will override the MSI configuration).

4. Validate Runtime and Bundle Compatibility #

• Confirm your Function App runs on Functions runtime version ~4 (compatible with 2.x extension bundles).
• Check that the extension bundle is successfully installed post-deployment: Go to Function App > Extensions > Verify the bundle version falls in the 2.x range.

5. Audit Workflow Connections #

Even if AzureWebJobsStorage is fixed, some workflow triggers/actions might still use key-based storage connections:

• Open each workflow in Azure Portal.
• For any storage-related connectors, confirm they're configured to use MSI instead of access keys.

内容的提问来源于stack exchange，提问作者JCallico