Saturday, 6:40 a.m. Eleven thousand SKUs, 2,400 bin locations, one warehouse manager holding a clipboard and a printed pick list. The system switch was scheduled for Sunday midnight.
By 9 a.m. we knew the count was off by 6% in the fast-mover zone. At a food-grade packaging distributor, 6% wrong in the wrong aisle means trucks leave short. This is the part of ERP Consulting nobody puts on the slide deck.
The Thursday decision that saved the weekend
Two days earlier we had set a go/no-go rule in writing: if fast-mover accuracy was below 97%, we would freeze the top 300 SKUs manually and switch anyway, with a paper backup for one week.
Everyone hated the paper backup. It felt like admitting failure. It also meant the warehouse could keep shipping while the team fixed counts in parallel. Having a pre-agreed fallback is what makes a cutover survivable, not heroics at 2 a.m.
- Define go/no-go thresholds in writing at least 10 days out, with the specific numbers and who decides.
- Freeze transactions in the last 24 hours for physical moves only. Receiving and shipping continue; put-away waits.
- Print the top 200 to 300 SKUs by volume as a paper fallback. Two hours of printing beats a day of lost orders.
- Staff the floor with two people per zone who know the product, not just the system.
What went wrong anyway
The receiving dock had three trucks booked for Monday morning, and the new system required a purchase order match that two suppliers never sent. The receiving clerk did what any sensible person does under pressure — she keyed the receipt against a fake PO.
We caught it Tuesday on the exception report. The lesson is not “train harder”. The lesson is to give people a sanctioned workaround. We added an “unmatched receipt” path with a 24-hour cleanup queue. Keyed errors dropped from 40 a week to 6.
The checklist we now use for every cutover
- Ten days out: agree the go/no-go numbers and write them on one page.
- Five days out: freeze physical moves, run a full fast-mover count, print fallback picks.
- Two days out: walk the floor with the warehouse lead and test three real orders end to end.
- Day one after go-live: sit a person at the dock for the entire shift. Do not leave it to a help desk ticket.
The warehouse hit 99.1% accuracy six weeks later and the paper backup was retired in nine days. The habit worth copying is the written go/no-go page, signed before anyone is tired. That single document is the cheapest insurance in ERP Consulting.