A staging environment only helps if it resembles production.
WHAT MUST MATCH
PHP version and enabled extensions Database version Web server configuration, as far as possible The same plugins and themes at the same versions Similar data volume, so performance problems appear
WHAT SHOULD DIFFER
Debug mode, on in staging Mail, caught rather than sent API keys, test rather than live Search engine indexing, discouraged Access, restricted
REFRESHING FROM PRODUCTION
Periodically copy production data down to staging so tests are realistic. Anonymise personal data if staging is less protected.
Never copy staging up to production. That destroys everything written since the copy, which on a shop means every order.
WHAT DRIFTS
Configuration changed on production and not on staging Plugins updated in one and not the other Data volume, as production grows and staging stays small
Check periodically rather than assuming they still match.
THE FAILURE
A bug that appears only in production, because staging was never really the same.
