Verify all production data backups are complete, tested, and stored in secure location

Implement change freeze across all systems and notify all stakeholders

Send final notification to all users about system downtime and expected duration

Activate maintenance mode on all user-facing applications

Gracefully shutdown legacy ERP application servers in correct sequence

Perform final incremental data sync from legacy to new system with validation

Update network routing and firewall rules for new infrastructure

Switch DNS to point to new infrastructure with TTL consideration

Bring up new ERP system and verify all services are running

Update and test all integration endpoints and API connections

Execute comprehensive smoke tests on all critical business functions

Verify all integration points are functioning with downstream systems

Verify system performance meets baseline requirements under load

Verify all security controls are active and functioning

Open system access to pilot user group for initial validation

Monitor system behavior with real user load from pilot group

Enable access for first wave of users (50%)

Monitor system stability with 50% user load

Enable access for remaining users (100%)

Remove maintenance mode and restore normal operations

Send success notification to all stakeholders and users

Enhanced monitoring and support for first 24 hours post-cutover

Begin controlled shutdown of legacy infrastructure

Conduct comprehensive lessons learned session with all teams

Configure integration with external vendor system

Update mobile app configuration to point to new backend