Issue #3106918 by longwave, mondrake, Gábor Hojtsy: Drop support of PHPUnit 6 in Drupal 9 because it will never get used anyway

Issue #3104538 by Hardik_Patel_12, Harshal Pradhan, ravi.shankar: Type hint "\Drupal\Core\Session\AccountInterface" missing

Issue #3108021 by alexpott, lauriii: Set $defaultTheme for install profiles using configuration install

Issue #3103993 by Hardik_Patel_12, Rangaswini, alexpott: Value returned from FileSystem methods are not checked in streamUploadData() function

Issue #3104534 by Hardik_Patel_12: Expected type hint "GetResponseEvent"; found "FilterResponseEvent" for $event

Issue #3107783 by Krzysztof Domański, ravi.shankar, longwave, alexpott: Method $class::buildBasicRenderable() call uses 4 parameters, but method signature uses 3 parameters

Issue #3101138 by andypost, pratik_kamble, kishor_kolekar, alexpott: UpdateSettingsForm should call parent constructor

Revert "Issue #3101543 by lauriii, bnjmnm, ravi.shankar: Update core JavaScript dependencies listed in package.json"

This reverts commit 2dadb738.

Issue #3101543 by lauriii, bnjmnm, ravi.shankar: Update core JavaScript dependencies listed in package.json

Issue #3108803 by k4v, ifrik, Gogowitsch: Error "default.settings.php should not be changed" during install

Issue #3098250 by alexpott, longwave, Wim Leers, lauriii: Remove all @deprecated code in \Drupal\Core\Extension

Issue #3098521 by Gnanagowthaman sankar, mandclu, penyaskito: drupal_installation_attempted() deprecation referencing wrong change record

Issue #3015699 by alexpott, longwave, johndevman, Berdir: Properly deprecate MENU_MAX_MENU_NAME_LENGTH_UI

Issue #3108851 by JeroenT, Berdir, Wim Leers: Remove deprecated node.module action plugins and leftovers

Issue #3097890 by martin107, longwave, andypost, lauriii: Remove all @deprecated code in core themes

Issue #3101130 by Krzysztof Domański, DukeandGrace: ConfigEntityQueryTest::testCaseSensitivity can randomly fail

Issue #3081145 by Berdir, andypost, longwave, catch, tim.plunkett, larowlan: Remove BC layers in the Plugin component

Issue #3097879 by andypost, longwave, Berdir, larowlan: Remove all @deprecated code in \Drupal\Core\Database

Issue #3087644 by jibran, Berdir, alexpott, longwave, Wim Leers, amateescu, catch, xjm, larowlan, dpi, quietone: Remove Drupal 8 updates up to and including 88**

Issue #2937782 by quietone, jofitz, yo30, heddn, Wim Leers, catch: Create trait for getDefinitionFromEntity

Issue #3108071 by tstoeckler, longwave, idebr: Remove IE9 workaround from responsive-image.html.twig

Issue #3074993 by tedbow, kim.pepper, bnjmnm, drumm, xjm, tim.plunkett, Gábor Hojtsy, alexpott: Use "current" in update URLs instead of CORE_COMPATIBILITY to retrieve all future updates

Issue #3100147 by gapple, longwave: Remove @import parsing from Drupal.AjaxCommands.prototype.add_css

Issue #3105288 by Hardik_Patel_12, snehalgaikwad: Expected type hint "WorkflowInterface"; found "WorkflowTypeInterface"

Issue #3104354 by longwave, TravisCarden, xjm, catch, alexpott, Wim Leers: Update Laminas components including Diactoros