Troubleshooting Common Azure Development Issues

This guide helps you diagnose and resolve frequently encountered problems when developing applications on Microsoft Azure.

Tip: Before diving into specific issues, ensure you have reviewed the Azure Development Best Practices. Often, adherence to best practices can prevent many common problems.

1. Connectivity Issues

1.1 Application Cannot Connect to Azure Services

Symptoms: Timeouts, connection refused errors, or network unreachable messages when your application tries to communicate with Azure services (e.g., Azure SQL Database, Azure Storage, Azure Cosmos DB).

Check Network Security Groups (NSGs): Ensure that the NSGs associated with your Azure resources allow inbound and outbound traffic on the required ports (e.g., 1433 for SQL, 443 for storage).
Firewall Rules: Verify that any OS-level firewalls or network firewalls between your application and Azure services are configured correctly.
Service Endpoints/Private Endpoints: If you are using these for private connectivity, confirm they are set up correctly and your VNet is configured to use them.
DNS Resolution: Ensure that your application can resolve the DNS names of the Azure services.
Service Status: Check the Azure Service Health dashboard for any ongoing incidents affecting the service you are trying to reach.

1.2 Local Development Environment Connectivity

Symptoms: Unable to connect to Azure services from your development machine (e.g., Visual Studio, VS Code).

Azure CLI/PowerShell Authentication: Ensure you are logged in and authenticated correctly. Run az login or Connect-AzAccount.
Proxy Settings: If you are behind a corporate proxy, configure your development tools and SDKs to use the proxy.
Antivirus/Firewall: Temporarily disable your local antivirus or firewall to see if it's interfering with connections.

2. Authentication and Authorization Errors

2.1 Unauthorized Access (HTTP 401/403)

Symptoms: Your application receives 401 Unauthorized or 403 Forbidden responses from Azure services.

Service Principal Permissions: If using a Service Principal, verify its role assignments on the target Azure resource. Does it have the necessary permissions (e.g., "Reader", "Contributor")?
Managed Identity Configuration: If using a Managed Identity (System-assigned or User-assigned), ensure it's enabled for your Azure resource (e.g., App Service, VM) and has the correct role assignments.
Key Vault Secrets: If authenticating with keys or secrets stored in Azure Key Vault, confirm the secret name is correct and the identity accessing it has "Get" permissions on the secret.
Token Expiration: Ensure that authentication tokens are being refreshed before they expire.
Correct Credentials: Double-check that your application is using the correct Tenant ID, Client ID, Client Secret (or certificate), and Resource URL.

Security Note: Never hardcode credentials in your application. Use Azure Key Vault or Managed Identities for secure credential management.

3. Deployment Failures

3.1 Application Deployment Errors

Symptoms: Deployment processes (e.g., ARM templates, Bicep, CI/CD pipelines, `az webapp deploy`) fail with error messages.

Check Deployment Logs: Always examine the detailed logs provided by the deployment tool. These often contain specific error codes and messages from Azure.
Resource Provider Registration: Ensure the necessary Azure resource providers (e.g., Microsoft.Web, Microsoft.Storage) are registered in your subscription.
Quotas and Limits: Verify that you are not exceeding any subscription quotas or service limits (e.g., number of core in a region, storage account size).
Naming Conventions: Azure resource names must be globally unique and adhere to specific naming rules.
Dependencies: Ensure that dependent resources (e.g., a database for a web app) exist and are configured before deploying dependent resources.

3.2 Application Fails to Start After Deployment

Symptoms: Application deployed successfully but returns errors (e.g., 5xx server errors, blank page) or crashes shortly after startup.

Application Logs: Access application logs in Azure (e.g., App Service Logs, Container Logs). Look for exceptions, configuration errors, or missing dependencies.
Configuration Settings: Verify that all required application settings, connection strings, and environment variables are correctly configured in Azure.
Runtime Dependencies: Ensure that the correct runtime environment and dependencies are installed and compatible (e.g., correct .NET version, Node.js version, Python interpreter).
Startup Commands: For containerized applications, check that the `ENTRYPOINT` or startup commands are correct.

4. Performance and Scalability Issues

4.1 Slow Application Performance

Symptoms: High response times, slow queries, or application unresponsiveness.

Monitor Resource Utilization: Use Azure Monitor to check CPU, memory, network, and disk I/O for your compute resources (VMs, App Services, AKS nodes).
Database Performance: Analyze database queries, indexing, and resource scaling for Azure SQL Database, Cosmos DB, etc.
Network Latency: Investigate latency between your application and the services it interacts with. Consider using Azure regions closer to your users or deploying resources in the same region.
Application Profiling: Use application performance monitoring (APM) tools (like Application Insights) to identify bottlenecks within your code.

4.2 Scaling Issues

Symptoms: Application unable to handle increased load, leading to performance degradation or failures.

Autoscaling Rules: Review and tune your autoscaling rules for services like App Services, AKS, or Virtual Machine Scale Sets. Ensure they are configured to scale based on relevant metrics (CPU, request queue length).
Resource Limits: Check if you are hitting the limits of your current service tier or resource allocation.
Database Throughput: Ensure your database tier is provisioned with sufficient Request Units (RUs) or DTUs for your workload.

5. Monitoring and Logging

Effective monitoring and logging are crucial for diagnosing issues. Utilize tools like:

Azure Monitor: For collecting, analyzing, and acting on telemetry from your Azure and on-premises environments.
Application Insights: A powerful APM service that provides deep insights into your application's performance and usage.
Azure Log Analytics: For querying and analyzing log data.

Best Practice: Instrument your applications with Application Insights from the start to gain visibility into performance, errors, and dependencies.

6. Cost Management Issues

Symptoms: Unexpectedly high Azure bills.

Review Resource Usage: Use the Azure Cost Management + Billing service to identify which resources are consuming the most cost.
Right-sizing Resources: Ensure you are not over-provisioning resources. Downsize VMs, databases, or storage tiers if they are underutilized.
Unused Resources: Regularly identify and decommission resources that are no longer needed.
Data Egress Charges: Be mindful of data transfer costs, especially out of Azure regions.

If you encounter an issue not covered here, consider searching the official Azure documentation, community forums, or opening a support ticket.