2.5.1 is very old indeed. The latest version is currently
There are no breaking changes to upgrade from
2.9.2. You might wish to go over release notes to see what’s been introduced in the newer versions to take advantage of new features:
Non-breaking changes to keep in mind:
domainUserIdis a UUID from v2.6
trackPageViewgenerates a new ID with each page view from v2.7
trackSelfDescribingEventis an alias for
useCookiesare deprecated from v2.8. They will fire warnings if still used.