diff --git a/includes/wikia/VariablesBase.php b/includes/wikia/VariablesBase.php
index f2a4a1ae1225..ed09c4c7f1bd 100644
--- a/includes/wikia/VariablesBase.php
+++ b/includes/wikia/VariablesBase.php
@@ -8999,3 +8999,328 @@
  * @var $wgEnableHydralyticsExt
  */
 $wgEnableHydralyticsExt = true;
+
+/**
+ * List of Unicode characters for which capitalization is overridden in
+ * Language::ucfirst. The characters should be
+ * represented as char_to_convert => conversion_override. See T219279 for details
+ * on why this is useful during php version transitions.
+ *
+ * @warning: EXPERIMENTAL!
+ *
+ * @var array
+ */
+$wgOverrideUcfirstCharacters = [
+	'ß' => 'ß',
+	'ʼn' => 'ʼn',
+	'Dž' => 'Dž',
+	'dž' => 'Dž',
+	'Lj' => 'Lj',
+	'lj' => 'Lj',
+	'Nj' => 'Nj',
+	'nj' => 'Nj',
+	'ǰ' => 'ǰ',
+	'Dz' => 'Dz',
+	'dz' => 'Dz',
+	'ɪ' => 'ɪ',
+	'ͅ' => 'ͅ',
+	'ΐ' => 'ΐ',
+	'ΰ' => 'ΰ',
+	'և' => 'և',
+	'ა' => 'ა',
+	'ბ' => 'ბ',
+	'გ' => 'გ',
+	'დ' => 'დ',
+	'ე' => 'ე',
+	'ვ' => 'ვ',
+	'ზ' => 'ზ',
+	'თ' => 'თ',
+	'ი' => 'ი',
+	'კ' => 'კ',
+	'ლ' => 'ლ',
+	'მ' => 'მ',
+	'ნ' => 'ნ',
+	'ო' => 'ო',
+	'პ' => 'პ',
+	'ჟ' => 'ჟ',
+	'რ' => 'რ',
+	'ს' => 'ს',
+	'ტ' => 'ტ',
+	'უ' => 'უ',
+	'ფ' => 'ფ',
+	'ქ' => 'ქ',
+	'ღ' => 'ღ',
+	'ყ' => 'ყ',
+	'შ' => 'შ',
+	'ჩ' => 'ჩ',
+	'ც' => 'ც',
+	'ძ' => 'ძ',
+	'წ' => 'წ',
+	'ჭ' => 'ჭ',
+	'ხ' => 'ხ',
+	'ჯ' => 'ჯ',
+	'ჰ' => 'ჰ',
+	'ჱ' => 'ჱ',
+	'ჲ' => 'ჲ',
+	'ჳ' => 'ჳ',
+	'ჴ' => 'ჴ',
+	'ჵ' => 'ჵ',
+	'ჶ' => 'ჶ',
+	'ჷ' => 'ჷ',
+	'ჸ' => 'ჸ',
+	'ჹ' => 'ჹ',
+	'ჺ' => 'ჺ',
+	'ჽ' => 'ჽ',
+	'ჾ' => 'ჾ',
+	'ჿ' => 'ჿ',
+	'ᲀ' => 'ᲀ',
+	'ᲁ' => 'ᲁ',
+	'ᲂ' => 'ᲂ',
+	'ᲃ' => 'ᲃ',
+	'ᲄ' => 'ᲄ',
+	'ᲅ' => 'ᲅ',
+	'ᲆ' => 'ᲆ',
+	'ᲇ' => 'ᲇ',
+	'ᲈ' => 'ᲈ',
+	'ẖ' => 'ẖ',
+	'ẗ' => 'ẗ',
+	'ẘ' => 'ẘ',
+	'ẙ' => 'ẙ',
+	'ẚ' => 'ẚ',
+	'ὐ' => 'ὐ',
+	'ὒ' => 'ὒ',
+	'ὔ' => 'ὔ',
+	'ὖ' => 'ὖ',
+	'ᾀ' => 'ᾈ',
+	'ᾁ' => 'ᾉ',
+	'ᾂ' => 'ᾊ',
+	'ᾃ' => 'ᾋ',
+	'ᾄ' => 'ᾌ',
+	'ᾅ' => 'ᾍ',
+	'ᾆ' => 'ᾎ',
+	'ᾇ' => 'ᾏ',
+	'ᾈ' => 'ᾈ',
+	'ᾉ' => 'ᾉ',
+	'ᾊ' => 'ᾊ',
+	'ᾋ' => 'ᾋ',
+	'ᾌ' => 'ᾌ',
+	'ᾍ' => 'ᾍ',
+	'ᾎ' => 'ᾎ',
+	'ᾏ' => 'ᾏ',
+	'ᾐ' => 'ᾘ',
+	'ᾑ' => 'ᾙ',
+	'ᾒ' => 'ᾚ',
+	'ᾓ' => 'ᾛ',
+	'ᾔ' => 'ᾜ',
+	'ᾕ' => 'ᾝ',
+	'ᾖ' => 'ᾞ',
+	'ᾗ' => 'ᾟ',
+	'ᾘ' => 'ᾘ',
+	'ᾙ' => 'ᾙ',
+	'ᾚ' => 'ᾚ',
+	'ᾛ' => 'ᾛ',
+	'ᾜ' => 'ᾜ',
+	'ᾝ' => 'ᾝ',
+	'ᾞ' => 'ᾞ',
+	'ᾟ' => 'ᾟ',
+	'ᾠ' => 'ᾨ',
+	'ᾡ' => 'ᾩ',
+	'ᾢ' => 'ᾪ',
+	'ᾣ' => 'ᾫ',
+	'ᾤ' => 'ᾬ',
+	'ᾥ' => 'ᾭ',
+	'ᾦ' => 'ᾮ',
+	'ᾧ' => 'ᾯ',
+	'ᾨ' => 'ᾨ',
+	'ᾩ' => 'ᾩ',
+	'ᾪ' => 'ᾪ',
+	'ᾫ' => 'ᾫ',
+	'ᾬ' => 'ᾬ',
+	'ᾭ' => 'ᾭ',
+	'ᾮ' => 'ᾮ',
+	'ᾯ' => 'ᾯ',
+	'ᾲ' => 'ᾲ',
+	'ᾳ' => 'ᾼ',
+	'ᾴ' => 'ᾴ',
+	'ᾶ' => 'ᾶ',
+	'ᾷ' => 'ᾷ',
+	'ᾼ' => 'ᾼ',
+	'ῂ' => 'ῂ',
+	'ῃ' => 'ῌ',
+	'ῄ' => 'ῄ',
+	'ῆ' => 'ῆ',
+	'ῇ' => 'ῇ',
+	'ῌ' => 'ῌ',
+	'ῒ' => 'ῒ',
+	'ΐ' => 'ΐ',
+	'ῖ' => 'ῖ',
+	'ῗ' => 'ῗ',
+	'ῢ' => 'ῢ',
+	'ΰ' => 'ΰ',
+	'ῤ' => 'ῤ',
+	'ῦ' => 'ῦ',
+	'ῧ' => 'ῧ',
+	'ῲ' => 'ῲ',
+	'ῳ' => 'ῼ',
+	'ῴ' => 'ῴ',
+	'ῶ' => 'ῶ',
+	'ῷ' => 'ῷ',
+	'ῼ' => 'ῼ',
+	'ⅰ' => 'ⅰ',
+	'ⅱ' => 'ⅱ',
+	'ⅲ' => 'ⅲ',
+	'ⅳ' => 'ⅳ',
+	'ⅴ' => 'ⅴ',
+	'ⅵ' => 'ⅵ',
+	'ⅶ' => 'ⅶ',
+	'ⅷ' => 'ⅷ',
+	'ⅸ' => 'ⅸ',
+	'ⅹ' => 'ⅹ',
+	'ⅺ' => 'ⅺ',
+	'ⅻ' => 'ⅻ',
+	'ⅼ' => 'ⅼ',
+	'ⅽ' => 'ⅽ',
+	'ⅾ' => 'ⅾ',
+	'ⅿ' => 'ⅿ',
+	'ⓐ' => 'ⓐ',
+	'ⓑ' => 'ⓑ',
+	'ⓒ' => 'ⓒ',
+	'ⓓ' => 'ⓓ',
+	'ⓔ' => 'ⓔ',
+	'ⓕ' => 'ⓕ',
+	'ⓖ' => 'ⓖ',
+	'ⓗ' => 'ⓗ',
+	'ⓘ' => 'ⓘ',
+	'ⓙ' => 'ⓙ',
+	'ⓚ' => 'ⓚ',
+	'ⓛ' => 'ⓛ',
+	'ⓜ' => 'ⓜ',
+	'ⓝ' => 'ⓝ',
+	'ⓞ' => 'ⓞ',
+	'ⓟ' => 'ⓟ',
+	'ⓠ' => 'ⓠ',
+	'ⓡ' => 'ⓡ',
+	'ⓢ' => 'ⓢ',
+	'ⓣ' => 'ⓣ',
+	'ⓤ' => 'ⓤ',
+	'ⓥ' => 'ⓥ',
+	'ⓦ' => 'ⓦ',
+	'ⓧ' => 'ⓧ',
+	'ⓨ' => 'ⓨ',
+	'ⓩ' => 'ⓩ',
+	'ꞹ' => 'ꞹ',
+	'ff' => 'ff',
+	'fi' => 'fi',
+	'fl' => 'fl',
+	'ffi' => 'ffi',
+	'ffl' => 'ffl',
+	'ſt' => 'ſt',
+	'st' => 'st',
+	'ﬓ' => 'ﬓ',
+	'ﬔ' => 'ﬔ',
+	'ﬕ' => 'ﬕ',
+	'ﬖ' => 'ﬖ',
+	'ﬗ' => 'ﬗ',
+	'𐓘' => '𐓘',
+	'𐓙' => '𐓙',
+	'𐓚' => '𐓚',
+	'𐓛' => '𐓛',
+	'𐓜' => '𐓜',
+	'𐓝' => '𐓝',
+	'𐓞' => '𐓞',
+	'𐓟' => '𐓟',
+	'𐓠' => '𐓠',
+	'𐓡' => '𐓡',
+	'𐓢' => '𐓢',
+	'𐓣' => '𐓣',
+	'𐓤' => '𐓤',
+	'𐓥' => '𐓥',
+	'𐓦' => '𐓦',
+	'𐓧' => '𐓧',
+	'𐓨' => '𐓨',
+	'𐓩' => '𐓩',
+	'𐓪' => '𐓪',
+	'𐓫' => '𐓫',
+	'𐓬' => '𐓬',
+	'𐓭' => '𐓭',
+	'𐓮' => '𐓮',
+	'𐓯' => '𐓯',
+	'𐓰' => '𐓰',
+	'𐓱' => '𐓱',
+	'𐓲' => '𐓲',
+	'𐓳' => '𐓳',
+	'𐓴' => '𐓴',
+	'𐓵' => '𐓵',
+	'𐓶' => '𐓶',
+	'𐓷' => '𐓷',
+	'𐓸' => '𐓸',
+	'𐓹' => '𐓹',
+	'𐓺' => '𐓺',
+	'𐓻' => '𐓻',
+	'𖹠' => '𖹠',
+	'𖹡' => '𖹡',
+	'𖹢' => '𖹢',
+	'𖹣' => '𖹣',
+	'𖹤' => '𖹤',
+	'𖹥' => '𖹥',
+	'𖹦' => '𖹦',
+	'𖹧' => '𖹧',
+	'𖹨' => '𖹨',
+	'𖹩' => '𖹩',
+	'𖹪' => '𖹪',
+	'𖹫' => '𖹫',
+	'𖹬' => '𖹬',
+	'𖹭' => '𖹭',
+	'𖹮' => '𖹮',
+	'𖹯' => '𖹯',
+	'𖹰' => '𖹰',
+	'𖹱' => '𖹱',
+	'𖹲' => '𖹲',
+	'𖹳' => '𖹳',
+	'𖹴' => '𖹴',
+	'𖹵' => '𖹵',
+	'𖹶' => '𖹶',
+	'𖹷' => '𖹷',
+	'𖹸' => '𖹸',
+	'𖹹' => '𖹹',
+	'𖹺' => '𖹺',
+	'𖹻' => '𖹻',
+	'𖹼' => '𖹼',
+	'𖹽' => '𖹽',
+	'𖹾' => '𖹾',
+	'𖹿' => '𖹿',
+	'𞤢' => '𞤢',
+	'𞤣' => '𞤣',
+	'𞤤' => '𞤤',
+	'𞤥' => '𞤥',
+	'𞤦' => '𞤦',
+	'𞤧' => '𞤧',
+	'𞤨' => '𞤨',
+	'𞤩' => '𞤩',
+	'𞤪' => '𞤪',
+	'𞤫' => '𞤫',
+	'𞤬' => '𞤬',
+	'𞤭' => '𞤭',
+	'𞤮' => '𞤮',
+	'𞤯' => '𞤯',
+	'𞤰' => '𞤰',
+	'𞤱' => '𞤱',
+	'𞤲' => '𞤲',
+	'𞤳' => '𞤳',
+	'𞤴' => '𞤴',
+	'𞤵' => '𞤵',
+	'𞤶' => '𞤶',
+	'𞤷' => '𞤷',
+	'𞤸' => '𞤸',
+	'𞤹' => '𞤹',
+	'𞤺' => '𞤺',
+	'𞤻' => '𞤻',
+	'𞤼' => '𞤼',
+	'𞤽' => '𞤽',
+	'𞤾' => '𞤾',
+	'𞤿' => '𞤿',
+	'𞥀' => '𞥀',
+	'𞥁' => '𞥁',
+	'𞥂' => '𞥂',
+	'𞥃' => '𞥃',
+];
diff --git a/languages/Language.php b/languages/Language.php
index 3cc3456f4eca..081788865283 100644
--- a/languages/Language.php
+++ b/languages/Language.php
@@ -2168,7 +2168,7 @@ function uc( $str, $first = false ) {
 		if ( function_exists( 'mb_strtoupper' ) ) {
 			if ( $first ) {
 				if ( $this->isMultibyte( $str ) ) {
-					return mb_strtoupper( mb_substr( $str, 0, 1 ) ) . mb_substr( $str, 1 );
+					return $this->mbUpperChar( mb_substr( $str, 0, 1 ) ) . mb_substr( $str, 1 );
 				} else {
 					return ucfirst( $str );
 				}
@@ -2189,6 +2189,26 @@ function uc( $str, $first = false ) {
 		}
 	}
 
+	/**
+	 * Convert character to uppercase, allowing overrides of the default mb_upper
+	 * behaviour, which is buggy in many ways. Having a conversion table can be
+	 * useful during transitions between PHP versions where unicode changes happen.
+	 * This can make some resources unreachable on-wiki, see discussion at T219279.
+	 * Providing such a conversion table can allow to manage the transition period.
+	 *
+	 * @param string $char
+	 *
+	 * @return string
+	 */
+	protected function mbUpperChar( $char ) {
+		global $wgOverrideUcfirstCharacters;
+		if ( array_key_exists( $char, $wgOverrideUcfirstCharacters ) ) {
+			return $wgOverrideUcfirstCharacters[$char];
+		} else {
+			return mb_strtoupper( $char );
+		}
+	}
+
 	/**
 	 * @param $str string
 	 * @return mixed|string