How long does a 2.4.7 → 2.4.9 upgrade actually take?

Clean stores: 2-3 weeks end-to-end. Messy stores: 4-6 weeks. Honest typical breakdown:

• Audit + planning: 2-3 days. Inventory extensions, check vendor compat releases, scan custom code for PHP 8.3 deprecations, draft staging plan.
• Staging build: 3-5 days. composer require, resolve dependency conflicts, run setup:upgrade, fix broken extensions, rebuild static content.
• QA + UAT: 5-10 days. Smoke-test every storefront, run checkout end-to-end, validate B2B (if applicable), test reindex on prod-data snapshot, fix issues iteratively.
• Cutover: 1 day. Pre-warm caches, freeze deploys, run final data-sync, switch DNS/load-balancer, watch dashboards for 4 hours.
• Stabilisation: 14 days, parallel with normal ops. Rollback button armed for first 72h.

Multipliers: B2B in scope adds +30%, multi-store adds +1 week per storefront, ERP integration adds +2 weeks for handshake retest, Hyvä migration alongside doubles the calendar time.

The 2.4.7 → 2.4.9 hop is one of the cleaner ones, OpenSearch already in place, PHP 8.2 → 8.3 (or 8.4) is the main framework lift, and the extension matrix is mostly clean by mid-2026.