Modern defence platforms rely on connected software for sensors, communications, mission planning and autonomy. Over long lifecycles they need constant capability and security updates, and each change can affect interfaces, data formats and real-time behaviour. The talk shows how version-controlled builds, SBOMs, dependency management and interface contracts keep releases identifiable and reproducible. A Software Update Management System (SUMS) links code, tests, approvals, deployed versions and vulnerabilities in one traceability chain. In operation, updates are signed, verified against the target platform, rolled out in stages and monitored, with rollback if something goes wrong. Together these practices keep systems safe, secure, interoperable and mission-ready.