Not every ugly back office needs a rebuild, and not every OA that still opens is worth repairing. Weigh three things: are the flows still right, can you still change the tech, and should data and accounts be inherited.
Leave, expenses, and seal routing still match the org; master data is intact; the pain is an old UI, hard phone approve, and weak chase. Adding to-dos, role-following permissions, and a contract ledger on the existing structure is lower risk, and training does not start from zero.
The vendor is gone and you cannot get source; permissions are written on names; flows still follow a ten-year-old org chart; packaged modules will not change. More patches will cost more than a rebuild, and the more you patch, the more people route around it.
When the vendor is gone, extend often has no construction surface. The replacement list: see Replacing a vendor-abandoned OA: what to watch. Packaged OA locks fields and nodes—it looks like a system while work stays in the group; see A packaged OA nobody uses is almost as bad as having none.
Rebuild is not “unroll ERP.” Get high-frequency approvals and permissions right first; inventory, orders, and basic finance can wait for phase two; see Do you need a full ERP?. How to split in-flight versus archive: see How to migrate data from a legacy OA.
After you choose rebuild, the fear is “new system live, old tickets gone.” List ticket-number rules printed in policy, contracts, and audit samples. Map what you can; hang the rest read-only on the old library. Rebuild the org by role—do not copy ten-year-old part-time approvers as-is. How permissions survive a transfer: see How to-dos and permissions survive when a manager leaves.
If you extend, fix phone to-dos and timeout chase before a reskin. Many “we must rebuild” complaints are managers approving outside while nobody clicks in the system. If you rebuild, do not shut the old site first; preview the new site, then cut—avoid payroll and seal peaks in the window.
When DaXi assesses a legacy OA, we ask: can flows still change, do accounts follow roles, can phones approve. Send the live situation to the Management systems service page. The full path: see From brief to launch: how a management system is built. Cycle and money depend on which phase you stop at; see What an OA / management system costs, and how long it takes.
Say whether the vendor is still there, whether flows are still right, and whether permissions follow names or roles. Engineering will return an extend or rebuild scope—not a default teardown.