Migrate PHP 7.4 to PHP 8.0

When to use

• The user hits PHP 8.0 breaking changes (reserved match keyword, magic method signatures, removed functions, stricter comparisons) while upgrading from 7.4.
• The user wants to modernize a legacy PHP project and adopt PHP 8.0 syntax such as constructor promotion, match, and union types.
• The user wants to migrate or upgrade a codebase from PHP 7.4 to PHP 8.0.

When NOT to use

• Do not use this skill when the codebase already runs on PHP 8.0 or later; use the target-version skill for new 8.1+ features instead.
• Do not use this skill for a greenfield project that has no PHP 7.4 code to carry forward.

Core guidance