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 0 <`Deal with major upgrades in PHP>`_.

Related : Version, Semantic Versioning, Forward Compatible, Legacy, Maintenance, Migration