The cutover window hour by hour — freeze, extract, load, reconcile, verify, open — with the extra complication that a retained Plex MES means the freeze is partial. Four-corner reconciliation with named owners and signed thresholds. Go/no-go decision points, the rollback plan, day-one readiness, the hypercare model and what happens to the Plex tenant afterwards.
Chapters 1 and 2 built the programme and the engine. This chapter is about the window that either validates or exposes both: the freeze, the load, the reconciliation, and the weeks of hypercare that follow before anyone can honestly say the cutover worked.
If Plex MES is retained as the shop-floor system of record, the cutover freeze is not a clean lock-out — it is a partial freeze with an active integration boundary:
[!TIP] Print the runbook and walk through it with the cutover team at least twice before the real event. The dress rehearsal tests the pipeline; the walk-through tests whether the humans know which step is theirs, what triggers it, and what they do if it fails.
Four separate reconciliation checks, each with a named owner, a named source report, a named target report and a signed tolerance threshold, must pass before go-live. "Pass" means an explicit, signed variance of zero (or an explained, approved rounding tolerance) for every account, every entity, every dimension — not a total that looks…
Rollback is by D365 environment restore (Power Platform Admin Center point-in-time restore to the pre-cutover snapshot) plus Plex un-freeze (to the extent Plex was constrained at all). Rollback is available until the go-live gate.
[ ] D365 user accounts provisioned and tested (each user can log in and reach their workspace) [ ] Label printers and barcode scanners configured and tested in the D365 Warehouse management mobile app [ ] EDI partners switched — broker maps now point at D365 entities, not Plex [ ] MES integration live — business-events endpoint receiving…
Hypercare is the period between go-live and handover to steady-state support. It is staffed at a higher level than normal operations because the first weeks surface defects that no amount of testing catches — defects that only appear when real users, real volumes and real business timing apply simultaneously.
A Plex tenant is SaaS. It does not sit on a shelf in a data centre you own. When you stop paying, access is revoked. This creates three obligations:
A Plex cutover carries two complications that most on-premises migrations do not: no confirmed technical freeze mechanism and, if MES is retained, a partial freeze with an active integration boundary that must switch over during the window. The four-corner reconciliation is the gate — not a formality.