* $wgBug34832TransitionalRollback has been removed.
* (bug 29472) $wgUseDynamicDates has been removed and its functionality
disabled.
+* $wgVectorUseIconWatch is now enabled by default.
=== New features in 1.21 ===
* (bug 38110) Schema changes (adding or dropping tables, indices and
to action=feedwatchlist
* WDDX formatted output will actually be formatted (and normal output will no
longer be), and will no longer choke on booleans.
+* The JSON output formatter now leaves forward slashes unescaped to improve human
+ readability of URLs and similar strings. Also, a "utf8" option is now provided
+ to use UTF-8 encoding instead of hex escape codes for most non-ASCII characters.
+* action=opensearch no longer silently ignores the format parameter.
+* action=opensearch now supports format=jsonfm.
=== API internal changes in 1.21 ===
* For debugging only, a new global $wgDebugAPI removes many API restrictions when true.
- ShowStats -> ShowSiteStats.
* BREAKING CHANGE: (bug 38244) Removed the mediawiki.api.titleblacklist module
and moved it to the TitleBlacklist extension.
+* The Special:ActiveUsers special page was removed
+* BREAKING CHANGE: Implementation of MediaWiki's JS and JSON value encoding
+ has changed:
+** MediaWiki no longer supports PHP installations in which the native JSON
+ extension is missing or disabled.
+** XmlJsCode objects can no longer be nested inside objects or arrays.
+ (For Xml::encodeJsCall(), this individually applies to each argument.)
+** The sets of characters escaped by default, along with the precise escape
+ sequences used, have changed (except for the Xml::escapeJsString()
+ function, which is now deprecated).
+* BREAKING CHANGE: The Services_JSON class has been removed; if necessary,
+ be sure to upgrade affected extensions at the same time (e.g. Collection).
+* Calling Linker methods using a skin will now output deprecation warnings.
== Compatibility ==