Change management for an ERP project.
People resist the loss, not the software. Explain the why, make managers the trainers, and listen hard in the first 90 days.
Change management becomes a workstream of posters when nobody has said, out loud, what people are being asked to give up.
Say the loss
A new ERP takes away a private spreadsheet, a private way of looking busy, sometimes a job that existed to retype what another system already knew. If you only talk about benefits, people will supply the loss themselves, and their version will be worse than the truth. Tell them what stops, what stays, and what they will be better at.
Do it in their words. "Single source of truth" is not a reason to a collector who is worried about a target. "You will stop rebuilding this report every Sunday" might be.
Managers are the trainers
People copy their manager, not the project newsletter. If the manager still asks for the old file, the old file will survive the go-live party. Prepare managers before the wider team. They should be able to run one real transaction and answer the first five objections. If they cannot, the classroom training will not land.
The first 90 days are the design
The process you configured is a hypothesis. The first weeks of real orders will show the steps nobody does and the fields everyone fakes. Collect that on purpose: a short list, reviewed every week, with a visible decision to fix, defer, or insist. Insisting without listening is how you get shadow systems. Listening without a decision is how the project never ends.
Change sticks when people can see that someone heard the friction and removed it. That is the whole programme.