Upgrade¶
An upgrade refers to the process of updating or replacing an existing installation of PHP or any library or component with a newer version. Major upgrade refers to a change in the first digit of the version, while minor upgrades are for the other numbers in the version.
An upgrade often require a migration: the current code has to be made compatible with the current version, but also with the upcoming version.
See also Deal with major upgrades in PHP and The Quiet Shift Reshaping PHP Security.
Related : Version, Semantic Versioning, Forward Compatible, Legacy, Maintenance, Migration