App Services Troubleshooting Guide

Step 1: Check Deployment Logs

Review the deployment logs in the Azure portal for specific error messages. These logs often pinpoint the exact failure point.

Navigate to your App Service -> Deployment Center -> Logs

Step 2: Verify Credentials and Permissions

Ensure that the user account or service principal used for deployment has the necessary contributor or owner role on the App Service or resource group.

Step 3: Examine Build Outputs

If using CI/CD, check the build logs from your CI/CD pipeline. Ensure all build steps complete successfully before deployment.

Step 4: Review Application Dependencies

Make sure all required libraries and packages are correctly listed in your project's manifest file (e.g., package.json for Node.js, requirements.txt for Python) and are compatible.

Step 1: Enable Application Logging

Configure detailed logging for your application. For many frameworks, this involves setting specific environment variables or configuration settings.

Example for Node.js (Express):

app.use(express.json());
app.use(express.urlencoded({ extended: false }));
// Enable detailed error logging in production
if (process.env.NODE_ENV === 'production') {
    // Configure your logger (e.g., Winston, Pino) here
}

Step 2: Check App Service Logs

Access the App Service logs in the Azure portal for detailed error messages and stack traces.

App Service -> Monitoring -> Log stream

You can also enable "Application Logging (Filesystem/Blob)" and "Web server logging" for more comprehensive insights.

Step 3: Monitor Resource Utilization

Use the "Metrics" blade in the Azure portal to check CPU, memory, and network usage. High utilization can indicate performance bottlenecks or resource leaks.

Step 4: Review Application Configuration

Ensure all necessary connection strings, API keys, and environment variables are correctly configured in the App Service's "Configuration" section.

Step 1: Profile Your Application

Use application performance monitoring (APM) tools like Application Insights or profile your application locally to identify performance bottlenecks in your code.

Step 2: Optimize Database Queries

Analyze and optimize slow-running database queries. Ensure proper indexing is in place.

Step 3: Scale Your App Service Plan

If resource utilization is consistently high, consider scaling up your App Service plan to a higher tier with more CPU, memory, and I/O.

Step 4: Implement Caching

Utilize caching mechanisms (e.g., Redis Cache) for frequently accessed data to reduce database load and improve response times.

Step 1: Verify Connection Strings

Double-check all connection strings in the App Service "Configuration" section for accuracy, including server names, usernames, and passwords.

Step 2: Check Firewall and NSG Rules

If connecting to a database or service with a firewall, ensure the App Service's outbound IP addresses are allowed. Review NSG rules if using VNet integration.

App Service -> Networking -> Outbound IP addresses

Step 3: Test DNS Resolution

Use the "Kudu" console (Advanced Tools) to test DNS resolution for the target service.

App Service -> Advanced Tools -> Go -> Debug console (CMD/PowerShell)
# Example: nslookup your_database_server.database.windows.net