What PHP 8.3 changes for WordPress plugins

These are the functions, constants and settings that PHP 8.3 removes, deprecates or no longer ships, with what to use instead. A removed function or constant stops a plugin with a fatal error when that code runs. A deprecated one keeps working and logs a notice.

Check your site with Bumpcheck, free Try it in your browser

Deprecated

assert_options(). Use the zend.assertions INI setting.
ASSERT_ACTIVE, ASSERT_BAIL, ASSERT_CALLBACK, ASSERT_EXCEPTION, ASSERT_WARNING, MT_RAND_PHP. The constant is deprecated.
assert.active, assert.bail, assert.callback, assert.exception, assert.warning. Use zend.assertions.

Bumpcheck also checks syntax changes, such as array offsets with curly braces and constructors named after their class. The full list is on the plugin page.