Bug Fixing for controlled technical improvement.

Compare business impact, root cause, support status, test coverage and migration risk over a two-to-three year horizon. A targeted fix suits an isolated defect. A rebuild needs justification from structural constraints — an unsupported platform, changes that routinely break unrelated features, or an inability to hire people willing to work on it.

With an audit: recovering access and accounts, inventorying repositories and environments, establishing dependency and version state, verifying that backups actually restore, and documenting how the system really deploys. That produces a risk picture before anyone commits to maintaining or replacing it.

Cost follows system size and how much is undocumented. The deliverable should be a prioritised findings list with reproduction steps, severity, effort estimates and a recommended sequence — not a tool export. It should be actionable by your own developers if you choose to implement it internally.

Usually, provided source and access exist. The practical questions are whether the runtime is still supported, whether dependencies can still be installed, and whether a working local environment can be reconstructed. Where a platform is genuinely end-of-life, containment plus a staged migration is more honest than indefinite maintenance.

Security patches are urgent. Minor versions should be routine and batched. Major versions need planning, regression tests and a rollback path. The expensive position is deferring everything until a security disclosure forces several major upgrades simultaneously under time pressure.

Updates and patching, backups with tested restores, uptime and error monitoring, defect response inside an agreed window, small changes, and periodic reporting on what changed and what risk remains. New features and redesigns should be scoped separately so the retainer stays predictable.

Usually, through a staged transition rather than a switchover. Common patterns are running old and new side by side behind a routing layer, migrating one workflow at a time, or rebuilding the frontend while the existing backend keeps operating. Each adds temporary complexity that has to be planned for.

Define the outcome and acceptance criteria before starting, migrate in vertical slices that each deliver working value, and keep the system shippable throughout. Projects overrun when the goal is described as replacing the system rather than as a sequence of specific, verifiable improvements.