Issue #2638140 by alexpott, dawehner, cilefen, xjm, Fabianx, Xano, catch: Error logging should log a backtrace consistently

Issue #2572777 by andypost, alexpott, attiks, andriyun: Fix 'Squiz.Strings.ConcatenationSpacing' coding standard

Issue #2700661 by anoopjohn: Ensure core compliance to Drupal.Commenting.FunctionComment.ParamCommentIndentation (part 1).

Issue #2576533 by alexpott, stefan.r, Wim Leers, dawehner, xjm, effulgentsia, catch: Rename SafeStringInterface to MarkupInterface and move related classes

Issue #2562487 by stefan.r, chx, tim.plunkett, dawehner, alexpott: Get better error reporting from __toString

Issue #2501319 by joelpittet, cwells, stefan.r, YesCT, nlisgo, Cottser, cmanalansan, dawehner, xjm, alexpott, josephdpurcell: Remove SafeMarkup::set() in Error::renderExceptionSafe() and _drupal_log_error() and improve backtrace formatting consistency in _drupal_log_error(), Error::renderExceptionSafe(), and DefaultExceptionSubscriber::onHtml()

Issue #2547127 by dawehner, Wim Leers, legolasbo, davidhernandez, webchick: [regression] Empty messages container appearing when a Notice occurs

Issue #2540438 by znerol, timmillwood: Invalid format string when falling back to error_log in _drupal_log_error()

Issue #2509898 by dawehner, znerol, larowlan, lauriii, Aki Tendo, Wim Leers: Additional uncaught exception thrown while handling exception after service changes

Issue #2407195 by Wim Leers, Fabianx, joelpittet, lauriii, Crell: Move attachment processing to services and per-type response subclasses

Issue #2478119 by znerol, andypost: Replace references to Session Manager with references to Session

Issue #1818692 by mbrett5062, lokapujya, David_Rothstein, blacklight4: Improve the maintenance page error message (rollback)

Issue #2451085 by dawehner, Arla: _drupal_log_error() passes NULL to ThemeManager::setActiveTheme(), violating its typehint

Issue #2317913 by jhedstrom: Early error handling can result in fatal error (Call to a member function get() on a non-object)

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

Issue #1825952 by Fabianx, joelpittet, bdragon, heddn, chx, xjm, pwolanin, mikey_p, ti2m, bfr, dags, cilefen, scor, mgifford: Turn on twig autoescape by default

Issue #2016629 by larowlan, neclimdul, sun, alexpott, jibran, ParisLiakos, donquixote, effulgentsia, msonnabaum: Refactor bootstrap to better utilize the kernel.

Revert "Issue #2016629 by larowlan, neclimdul, sun, alexpott, jibran, ParisLiakos, donquixote, effulgentsia, msonnabaum: Refactor bootstrap to better utilize the kernel."

This reverts commit cda051c4.

Issue #2016629 by larowlan, neclimdul, sun, alexpott, jibran, ParisLiakos, donquixote, effulgentsia, msonnabaum: Refactor bootstrap to better utilize the kernel.

Issue #2089433 by ianthomas_uk, grom358, herom, thedavidmeister, visabhishek, longwave, Sweetchuck: Remove uses of deprecated XSS filter functions.

Revert "Issue #2218039 by sun, dawehner: Render the maintenance/install page like any other HTML page."

Broke update.php.

This reverts commit 10b03890.

Issue #2192649 by sun, chakrapani, sidharthap: Remove drupal_set_title() from installation and update process.

Issue #2187735 by ianthomas_uk, Sutharsan, andypost: Add removal information to docblock of all @deprecated functions.

Issue #2194111 by sun: Error handler throws exception when service container is not (fully) available yet.

Issue #2171683 by sun, alexpott, tstoeckler, larowlan: Remove all Simpletest overrides and rely on native multi-site functionality instead.

Revert "Issue #2171683 by sun, tstoeckler, larowlan: Remove all Simpletest overrides and rely on native multi-site functionality instead."

This reverts commit 91db25eb. Broke web
tests.