Troubleshooting Common Migration Issues

This comprehensive troubleshooting guide addresses common issues encountered during Azure migration projects and provides step-by-step resolution procedures.

🌐 Network Connectivity Issues

Unable to Connect to Azure Resources After Migration

Symptoms:

  • Applications cannot reach Azure services
  • Remote desktop/SSH connections fail
  • Database connections timeout
  • API calls return network errors

Diagnostic Steps:

  1. Check Network Security Groups (NSGs) 
    # List NSG rules for a specific VM
Get-AzNetworkSecurityGroup -ResourceGroupName "MyRG" | Get-AzNetworkSecurityRuleConfig
  2. Verify Azure Firewall Rules
    • Review firewall policies and rules
    • Check application and network rule collections
    • Validate destination IP ranges and ports
  3. Test DNS Resolution 
    # Test DNS resolution
nslookup myapp.azurewebsites.net
Resolve-DnsName myapp.azurewebsites.net

Solutions:

  • NSG Configuration: Add required inbound/outbound rules for application ports
  • DNS Settings: Update DNS servers to Azure-provided DNS or custom DNS
  • Route Tables: Verify user-defined routes don’t conflict with system routes
  • Service Endpoints: Configure VNet service endpoints for Azure services
  • Private Endpoints: Implement private endpoints for secure connectivity

ExpressRoute/VPN Connectivity Problems

Symptoms:

  • Intermittent connectivity between on-premises and Azure
  • High latency or packet loss
  • BGP routing issues

Diagnostic Steps:

  1. Check Connection Status 
    # Check VPN Gateway connections
Get-AzVirtualNetworkGatewayConnection -ResourceGroupName "MyRG"
  2. Review BGP Information 
    # Get BGP peer status
Get-AzVirtualNetworkGatewayBGPPeerStatus -ResourceGroupName "MyRG" -VirtualNetworkGatewayName "MyVPNGW"

Solutions:

  • BGP Configuration: Verify BGP peering and route advertisement
  • Bandwidth Monitoring: Check for bandwidth exhaustion
  • Redundancy: Implement multiple connections for high availability
  • Route Optimization: Review and optimize routing policies

⚡ Performance Issues

Application Performance Degradation

Symptoms:

  • Slow response times
  • High CPU or memory utilization
  • Database query timeouts
  • User complaints about application speed

Diagnostic Steps:

  1. Monitor Resource Utilization 
    # Get VM performance metrics
Get-AzMetric -ResourceId "/subscriptions/.../resourceGroups/MyRG/providers/Microsoft.Compute/virtualMachines/MyVM" -MetricName "Percentage CPU" -TimeGrain 00:05:00
  2. Check Storage Performance
    • Review IOPS and throughput metrics
    • Monitor storage latency
    • Check for storage throttling
  3. Network Performance Analysis
    • Monitor network in/out metrics
    • Check for network throttling
    • Analyze inter-service communication patterns

Solutions:

  • VM Right-Sizing: Upgrade to appropriate VM SKUs based on workload requirements
  • Storage Optimization:
    • Migrate to Premium SSD or Ultra Disk for high-performance workloads
    • Implement disk caching strategies
    • Consider Azure NetApp Files for enterprise workloads
  • Network Optimization:
    • Use accelerated networking for supported VM sizes
    • Implement proximity placement groups for low latency
    • Consider ExpressRoute for consistent performance

Database Performance Issues

Symptoms:

  • Query execution timeouts
  • High DTU/vCore utilization
  • Connection pool exhaustion
  • Blocking and deadlocks

Diagnostic Steps:

  1. Monitor Database Metrics 
    -- Check active sessions and blocking
SELECT * FROM sys.dm_exec_sessions WHERE status = 'running'
SELECT * FROM sys.dm_exec_requests WHERE blocking_session_id > 0
  2. Analyze Query Performance
    • Use Query Store for performance insights
    • Review execution plans for inefficient queries
    • Monitor wait statistics

Solutions:

  • Service Tier Scaling: Upgrade to higher service tiers or compute sizes
  • Index Optimization: Create missing indexes and remove unused ones
  • Query Optimization: Rewrite inefficient queries and update statistics
  • Connection Management: Implement connection pooling and retry logic
  • Read Replicas: Offload read workloads to read replicas

🔐 Authentication and Authorization Issues

Azure AD Integration Problems

Symptoms:

  • Users cannot authenticate to migrated applications
  • SSO not working properly
  • Permission errors when accessing resources
  • Application registration issues

Diagnostic Steps:

  1. Check Azure AD Connect Health 
    # Verify AD Connect sync status
Get-ADSyncConnectorRunStatus
  2. Review Application Registrations
    • Verify redirect URIs and API permissions
    • Check certificate expiration dates
    • Validate client secrets
  3. Monitor Sign-in Logs
    • Review Azure AD sign-in logs for failures
    • Check conditional access policy impacts
    • Analyze risk detections

Solutions:

  • Sync Configuration: Fix Azure AD Connect synchronization issues
  • Application Configuration: Update application settings for cloud authentication
  • Permission Grants: Ensure proper API permissions and admin consent
  • Certificate Management: Renew expired certificates and update applications
  • Conditional Access: Review and adjust conditional access policies

Service Principal and Managed Identity Issues

Symptoms:

  • Applications cannot access Azure resources
  • Key Vault access denied errors
  • Storage account authentication failures
  • Service-to-service authentication problems

Diagnostic Steps:

  1. Verify Service Principal Configuration 
    # Check service principal details
Get-AzADServicePrincipal -DisplayName "MyApp"
  2. Review Role Assignments 
    # List role assignments for a principal
Get-AzRoleAssignment -ObjectId "service-principal-object-id"

Solutions:

  • Role Assignment: Assign appropriate RBAC roles to service principals
  • Managed Identity: Enable and configure system or user-assigned managed identities
  • Key Vault Policies: Update access policies for service principals
  • Secret Management: Rotate secrets and update application configurations

💾 Data Migration and Integrity Issues

Data Loss or Corruption

Symptoms:

  • Missing records after migration
  • Data type conversion errors
  • Encoding issues with special characters
  • Referential integrity violations

Diagnostic Steps:

  1. Data Validation Queries 
    -- Compare record counts
SELECT COUNT(*) FROM SourceTable
SELECT COUNT(*) FROM TargetTable
   
-- Check for data type issues
SELECT * FROM TargetTable WHERE ColumnName IS NULL AND SourceColumnName IS NOT NULL
  2. Check Migration Logs
    • Review Azure Database Migration Service logs
    • Check for warnings and errors during migration
    • Validate data type mappings

Solutions:

  • Re-run Migration: Use incremental migration to catch missing data
  • Data Type Mapping: Review and correct data type conversions
  • Character Encoding: Ensure proper UTF-8 encoding for international characters
  • Constraint Validation: Temporarily disable constraints during migration, then re-enable
  • Backup Restoration: Restore from verified backups if corruption is detected

Database Connection Issues

Symptoms:

  • Connection timeout errors
  • SSL/TLS certificate errors
  • Authentication failures
  • Connection pool exhaustion

Diagnostic Steps:

  1. Test Connectivity 
    # Test SQL connection
Test-NetConnection -ComputerName "myserver.database.windows.net" -Port 1433
  2. Review Connection Strings
    • Validate server names and database names
    • Check authentication methods (SQL vs Azure AD)
    • Verify encryption settings

Solutions:

  • Firewall Rules: Configure server-level and database-level firewall rules
  • Connection String Updates: Update applications with new Azure SQL connection strings
  • SSL Configuration: Enable SSL/TLS and update certificate trust
  • Connection Pooling: Implement proper connection pooling strategies
  • Retry Logic: Add exponential backoff retry logic for transient failures

💰 Cost Management Issues

Unexpected Cost Overruns

Symptoms:

  • Azure bills higher than expected
  • Rapid consumption of Azure credits
  • Cost alerts firing frequently
  • Uncontrolled resource provisioning

Diagnostic Steps:

  1. Cost Analysis 
    # Get cost and usage data
Get-AzConsumptionUsageDetail -StartDate (Get-Date).AddDays(-30) -EndDate (Get-Date)
  2. Resource Inventory
    • Identify largest cost contributors
    • Review resource utilization metrics
    • Check for orphaned or unused resources

Solutions:

  • Budget Implementation: Set up budgets with automated alerts
  • Resource Tagging: Implement comprehensive tagging for cost allocation
  • Rightsizing: Use Azure Advisor recommendations for VM rightsizing
  • Reserved Instances: Purchase reserved capacity for predictable workloads
  • Automation: Implement auto-shutdown for dev/test environments
  • Governance: Use Azure Policy to prevent oversized resource deployment

Data Transfer Cost Issues

Symptoms:

  • High bandwidth charges
  • Unexpected egress costs
  • Cross-region data transfer fees

Solutions:

  • Traffic Analysis: Monitor data flows between regions and services
  • CDN Implementation: Use Azure CDN to reduce egress costs
  • Region Optimization: Collocate services in the same region where possible
  • Compression: Enable compression for web applications and APIs
  • Caching: Implement caching strategies to reduce data transfer

🚀 Migration Tool Issues

Azure Migrate Problems

Symptoms:

  • Discovery agent not reporting data
  • Assessment errors or incomplete data
  • Replication failures during migration
  • Performance impact on source systems

Diagnostic Steps:

  1. Check Agent Status 
    # Verify migration service connectivity
Test-NetConnection -ComputerName "*.migrate.azure.com" -Port 443
  2. Review Assessment Reports
    • Check for unsupported configurations
    • Review readiness status for each VM
    • Validate licensing recommendations

Solutions:

  • Agent Updates: Ensure latest versions of migration agents
  • Network Configuration: Open required ports and URLs for migration services
  • Permission Issues: Verify service accounts have proper permissions
  • Resource Limits: Check for throttling due to concurrent migrations
  • Source System Health: Ensure source systems are healthy before migration

Azure Site Recovery Issues

Symptoms:

  • Replication not starting or failing
  • High recovery point objective (RPO)
  • Test failover failures
  • Protection status warnings

Diagnostic Steps:

  1. Check Replication Health 
    # Get ASR replication status
Get-AzRecoveryServicesAsrReplicationProtectedItem -ProtectionContainer $Container
  2. Review Infrastructure
    • Verify mobility service installation
    • Check process server capacity
    • Validate network bandwidth

Solutions:

  • Mobility Service: Update or reinstall mobility service on VMs
  • Process Server Scaling: Add additional process servers for large environments
  • Network Optimization: Increase bandwidth or implement traffic prioritization
  • Disk Exclusion: Exclude non-critical disks from replication
  • Retention Policy: Adjust retention policies based on requirements

🔧 Post-Migration Issues

Application Functionality Problems

Symptoms:

  • Features not working as expected
  • Integration points failing
  • Configuration errors
  • Service dependencies broken

Diagnostic Steps:

  1. Application Logs Review 
    # Check Windows Event Logs
Get-EventLog -LogName Application -Newest 100 | Where-Object {$_.EntryType -eq "Error"}
  2. Service Dependencies
    • Map all external service dependencies
    • Test API connectivity and authentication
    • Verify configuration file settings

Solutions:

  • Configuration Updates: Update connection strings and service endpoints
  • Environment Variables: Set appropriate environment variables for Azure
  • Service Principal Configuration: Configure managed identities for Azure services
  • Load Balancer Configuration: Update health probes and backend pools
  • DNS Updates: Point DNS records to new Azure endpoints

Monitoring and Alerting Gaps

Symptoms:

  • No visibility into application performance
  • Missing alerts for critical issues
  • Inadequate logging
  • No operational dashboards

Solutions:

  • Azure Monitor Setup: Implement comprehensive monitoring across all resources
  • Application Insights: Add application performance monitoring
  • Log Analytics: Centralize logging with structured log collection
  • Alert Rules: Create proactive alerts for key metrics and thresholds
  • Dashboards: Build operational dashboards for different stakeholder groups

🆘 Emergency Procedures

Rollback Procedures

When to Execute Rollback:

  • Critical functionality failures that cannot be quickly resolved
  • Unacceptable performance degradation
  • Data integrity issues
  • Security vulnerabilities introduced

Rollback Steps:

  1. Immediate Actions
    • Stop new user traffic to Azure environment
    • Redirect traffic back to on-premises systems
    • Communicate status to stakeholders
  2. Data Synchronization
    • Assess data changes since migration
    • Implement data sync from Azure back to on-premises
    • Verify data integrity after rollback
  3. Service Restoration
    • Restart on-premises services if needed
    • Update DNS records to point to original systems
    • Verify all integrations are working

Escalation Procedures

Level 1 - Internal Team

  • Review documentation and knowledge base
  • Check with team members for similar issues
  • Attempt basic troubleshooting steps

Level 2 - Microsoft Support

  • Open Azure support ticket with appropriate severity
  • Provide detailed symptoms and troubleshooting steps taken
  • Include relevant logs and screenshots

Level 3 - Emergency Response

  • Engage Microsoft FastTrack or Premier Support
  • Consider emergency change procedures
  • Implement business continuity plans

📋 Prevention and Best Practices

Pre-Migration Validation

  • Comprehensive Testing: Test all migration procedures in non-production environments
  • Dependency Mapping: Document all application dependencies and integration points
  • Performance Baselines: Establish performance benchmarks before migration
  • Rollback Planning: Develop and test detailed rollback procedures

Monitoring and Alerting

  • Proactive Monitoring: Implement monitoring before issues occur
  • Alert Tuning: Configure alerts with appropriate thresholds to avoid noise
  • Dashboard Creation: Build dashboards for different operational teams
  • Log Retention: Implement appropriate log retention policies

Documentation and Knowledge Transfer

  • Runbook Development: Create detailed operational runbooks
  • Knowledge Base: Document solutions to common issues
  • Team Training: Ensure team members understand new Azure operations
  • Change Management: Implement proper change control processes

📞 Additional Resources

For complex issues, consider engaging:

  • Microsoft FastTrack for Azure
  • Microsoft Premier Support
  • Certified Azure Migration Partners

Last updated: May 2025