Issue #2448069 by a_thakur, JeroenT, Mile23: Remove usage and function update_project_storage() from update.compare.inc

Issue #2444231 by Wim Leers, nlisgo: Fix CacheableInterface so it makes sense (was: "Make Config objects & Entities implement CacheableInterface + add BubbleableMetadata::createFromCacheableObject()")

Issue #2459971 by Gábor Hojtsy: The langcode key on configuration files is not explicit in configuration schema

Issue #2457271 by rteijeiro, Palashvijay4O, Cottser: More cleanup of the 'themeable' documentation group

Issue #2457887 by prateekMehta, stefan.r, rpayanm, alexpott: Use Utility\SafeMarkup class instead of Utility\String for placeholder(), checkPlain(),format() functions

Issue #2367747 by Palashvijay4O, andypost, Alienpruts, Cottser, er.pushpinderrana, gaurav.pahuja, pfrenssen, rpayanm, vadim.hirbu: Remove usage of system_rebuild_theme_data()

Issue #2384049 by suntog, mikemiles86, lokapujya, arpitr: Remove deprecated function _update_fetch_data and its usage

Issue #2435493 by effulgentsia: Change String::format()'s '@' and '%' placeholders to be auto-escaped rather than always-escaped

Issue #2384035 by arpitr, mikemiles86, lokapujya: Remove deprecated function _update_refresh and its usage

Issue #2195183 by cleaver, sandykadam, elgordogrande, jhodgdon, joachim, Eda, hussainweb: document Batch API callbacks as callback implementations

Issue #2364157 by mpdonadio, dawehner, martin107, Berdir, pcambra, naveenvalecha, tim.plunkett: Replace most existing _url calls with Url objects

Issue #1987890 by Mile23, disasm, undertext, pwolanin: Convert update_test_mock_page() to a new style controller

Issue #2392319 by alexpott, effulgentsia: Config objects (but not config entities) should by default be immutable

Issue #2309737 by rpayanm, hussainweb, max-kuzomko, herom, millerbennett, ianthomas_uk, quietone, Sutharsan, sumitmadan, toddmbloom: Remove deprecated format_plural usage

Issue #2281619 by dawehner, tim.plunkett: Convert most direct usages within module code of routing related request attributes to use RouteMatchInterface instead

Issue #2395395 by alexpott, effulgentsia, Gábor Hojtsy: TestBase lacks a config method to be used consistently in tests

Issue #2358991 by JeroenT, ianthomas_uk, rpayanm, jamesdixon, er.pushpinderrana, Ashok Negi: Remove usage of drupal_mail()

Issue #2362227 by dawehner, mpdonadio, znerol, tim.plunkett, skipyT: Replace all instances of current_path()

Issue #2374201 by YesCT: Docs and quote coding standard follow-up from: Incorrect logic in creating url to fetch information about project updates

Issue #2349773 by mirom, Zekvyrin, subhojit777, lauriii: Twig Double escaping on modules' available updates page

Issue #2328111 by dawehner, martin107, neclimdul: Replace most instances of the DRUPAL_ROOT constant with the app.root container parameter.

Issue #2362205 by Devin Carlson | dawehner: Fixed admin/theme/install|update should point to admin/appearance/update|install.

Issue #2315849 by Devin Carlson | Gábor Hojtsy: Update status does not have tests with (semantic) Drupal 8 versions.

Issue #2350949 by Wim Leers: Add hook_page_attachments(_alter)() and deprecate hook_page_build/alter().

Issue #2340667 by YesCT, Pedro Lozano, alexpott, martin107: Protect Drupal\Core\Language\Language::id, and use getId().

Issue #2246675 by rpayanm, johnstorey, holly.ross.drupal | mgbellaire: Remove all unnecessary 'template' lines in hook_theme() declarations.