What Upgrade Guides Don't Say
Every major platform upgrade promises new capability. Release notes are full of what you gain. They're much quieter about what you might lose, and that second question is usually the one that actually determines whether an upgrade is safe to attempt.
A recent major Odoo version change removed the continuous, real-time inventory-valuation model that many manufacturers had built their accounting process around, and replaced it with a period-end approach. For a business whose reporting, costing, and month-end close all assumed real-time valuation, that's not a minor change. It's a different accounting rhythm.
Rebuilding What Was Lost
The honest response to that kind of change isn't to pretend it didn't happen, or to force the new version to behave like the old one at the platform level. It's to rebuild the specific behaviour a business actually depends on, as custom reporting layered on top of the new model, so the numbers people rely on daily keep meaning what they used to mean.
The Question Worth Asking Before an Upgrade
"What did we lose" is a question upgrade guides rarely answer honestly, because the answer depends on how each business actually uses the system, not on a generic list of removed features. For any manufacturer on an older major version weighing the next upgrade, that question, asked concretely, is worth more than a feature-comparison chart.
If your team is planning a major-version jump and isn't sure what quietly changes underneath your existing process, that's exactly the kind of check Majorbird runs before recommending a go-live date, not after.