diff --git a/CHANGES.md b/CHANGES.md
index 14beccce637..70b0afdf7b9 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -10,6 +10,7 @@ Fixed Issues:
 * [#2996](https://github.com/ckeditor/ckeditor4/issues/2996): Fixed: Table header "scope" attribute is incorrect for the "Headers: both" option in the [Table](https://ckeditor.com/cke4/addon/table) dialog.
 * [#4802](https://github.com/ckeditor/ckeditor4/issues/4802): Fixed: [Tableselection](https://ckeditor.com/cke4/addon/tableselection) caret moves to the previous cell after tabbing into the next cell and then removing its content.
 * [#5365](https://github.com/ckeditor/ckeditor4/issues/5365): Fixed: The value of the [`config.baseFloatZIndex`](https://ckeditor.com/docs/ckeditor4/latest/api/CKEDITOR_config.html#cfg-baseFloatZIndex) config variable is incorrectly applied to parent dialog when the child dialog is closed resulting in the dialog overlay covering up the dialog. Thanks to [JenoDK](https://github.com/JenoDK)!
+* [#5305](https://github.com/ckeditor/ckeditor4/issues/5305): Fixed: Anchor name can invalidly include spaces.
 
 ## CKEditor 4.20
 
diff --git a/plugins/link/dialogs/anchor.js b/plugins/link/dialogs/anchor.js
index 7f15dd2590e..a7c3b4ee999 100755
--- a/plugins/link/dialogs/anchor.js
+++ b/plugins/link/dialogs/anchor.js
@@ -136,10 +136,23 @@ CKEDITOR.dialog.add( 'anchor', function( editor ) {
 				label: editor.lang.link.anchor.name,
 				required: true,
 				validate: function() {
-					if ( !this.getValue() ) {
+					// https://html.spec.whatwg.org/multipage/dom.html#global-attributes
+					// The id attribute value must not contain any space characters (#5305).
+					// [ space, tabulation, line feed, new line, form feed, carriage return ]
+					var disallowedWhitespacesRegex = /[\u0020\u0009\u000a\u000c\u000d]/g,
+						content = this.getValue();
+
+					if ( !content ) {
 						alert( editor.lang.link.anchor.errorName ); // jshint ignore:line
 						return false;
 					}
+
+					// Disallow creating anchors with space characters (#5305).
+					if ( disallowedWhitespacesRegex.test( content ) ) {
+						alert( editor.lang.link.anchor.errorWhitespace ); // jshint ignore:line
+						return false;
+					}
+
 					return true;
 				}
 			} ]
diff --git a/plugins/link/lang/af.js b/plugins/link/lang/af.js
index c7b0c105654..a70d3f86438 100644
--- a/plugins/link/lang/af.js
+++ b/plugins/link/lang/af.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'af', {
 		title: 'Anker-eienskappe',
 		name: 'Ankernaam',
 		errorName: 'Voltooi die ankernaam asseblief',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'Op element Id',
diff --git a/plugins/link/lang/ar.js b/plugins/link/lang/ar.js
index a36a3208588..be9bd8b2e91 100644
--- a/plugins/link/lang/ar.js
+++ b/plugins/link/lang/ar.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'ar', {
 		title: 'خصائص الإشارة المرجعية',
 		name: 'اسم الإشارة المرجعية',
 		errorName: 'الرجاء كتابة اسم الإشارة المرجعية',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'إزالة الإشارة المرجعية'
 	},
 	anchorId: 'حسب رقم العنصر',
diff --git a/plugins/link/lang/az.js b/plugins/link/lang/az.js
index cfdd4c5fa18..2d72f7e0a6c 100644
--- a/plugins/link/lang/az.js
+++ b/plugins/link/lang/az.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'az', {
 		title: 'Xeşin seçimləri',
 		name: 'Xeşin adı',
 		errorName: 'Xeşin adı yanlışdır',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Xeşin adı sil'
 	},
 	anchorId: 'ID görə',
diff --git a/plugins/link/lang/bg.js b/plugins/link/lang/bg.js
index 64c0774417e..d089c9906cd 100644
--- a/plugins/link/lang/bg.js
+++ b/plugins/link/lang/bg.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'bg', {
 		title: 'Настройки на котва',
 		name: 'Име на котва',
 		errorName: 'Моля въведете име на котвата',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Премахване на котва'
 	},
 	anchorId: 'По ID на елемент',
diff --git a/plugins/link/lang/bn.js b/plugins/link/lang/bn.js
index 43dc6230dd4..9d72a7b8c6d 100644
--- a/plugins/link/lang/bn.js
+++ b/plugins/link/lang/bn.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'bn', {
 		title: 'নোঙর প্রোপার্টি',
 		name: 'নোঙরের নাম',
 		errorName: 'নোঙরের নাম টাইপ করুন',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'নোঙরের আইডি দিয়ে',
diff --git a/plugins/link/lang/bs.js b/plugins/link/lang/bs.js
index f1646bd4278..791473f3d04 100644
--- a/plugins/link/lang/bs.js
+++ b/plugins/link/lang/bs.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'bs', {
 		title: 'Anchor Properties',
 		name: 'Anchor Name',
 		errorName: 'Please type the anchor name',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'Po Id-u elementa',
diff --git a/plugins/link/lang/ca.js b/plugins/link/lang/ca.js
index a9ce1e358bf..9e1b4be2b8b 100644
--- a/plugins/link/lang/ca.js
+++ b/plugins/link/lang/ca.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'ca', {
 		title: 'Propietats de l\'àncora',
 		name: 'Nom de l\'àncora',
 		errorName: 'Si us plau, escriviu el nom de l\'ancora',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'Per Id d\'element',
diff --git a/plugins/link/lang/cs.js b/plugins/link/lang/cs.js
index aeef6db32c2..f31e93d5c6b 100644
--- a/plugins/link/lang/cs.js
+++ b/plugins/link/lang/cs.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'cs', {
 		title: 'Vlastnosti záložky',
 		name: 'Název záložky',
 		errorName: 'Zadejte prosím název záložky',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Odstranit záložku'
 	},
 	anchorId: 'Podle Id objektu',
diff --git a/plugins/link/lang/cy.js b/plugins/link/lang/cy.js
index 62b6cf5b837..1a60d79005d 100644
--- a/plugins/link/lang/cy.js
+++ b/plugins/link/lang/cy.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'cy', {
 		title: 'Priodweddau\'r Angor',
 		name: 'Enw\'r Angor',
 		errorName: 'Teipiwch enw\'r angor',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Tynnwch yr Angor'
 	},
 	anchorId: 'Gan Id yr Elfen',
diff --git a/plugins/link/lang/da.js b/plugins/link/lang/da.js
index 167d38d64aa..dcb301c573b 100644
--- a/plugins/link/lang/da.js
+++ b/plugins/link/lang/da.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'da', {
 		title: 'Egenskaber for bogmærke',
 		name: 'Bogmærkenavn',
 		errorName: 'Indtast bogmærkenavn',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Fjern bogmærke'
 	},
 	anchorId: 'Efter element-Id',
diff --git a/plugins/link/lang/de-ch.js b/plugins/link/lang/de-ch.js
index edde6e63490..a238c1a1437 100644
--- a/plugins/link/lang/de-ch.js
+++ b/plugins/link/lang/de-ch.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'de-ch', {
 		title: 'Ankereigenschaften',
 		name: 'Ankername',
 		errorName: 'Bitte geben Sie den Namen des Ankers ein',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Anker entfernen'
 	},
 	anchorId: 'Nach Elementkennung',
diff --git a/plugins/link/lang/de.js b/plugins/link/lang/de.js
index 4700f52df25..370b403eeba 100644
--- a/plugins/link/lang/de.js
+++ b/plugins/link/lang/de.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'de', {
 		title: 'Ankereigenschaften',
 		name: 'Ankername',
 		errorName: 'Bitte geben Sie den Namen des Ankers ein',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Anker entfernen'
 	},
 	anchorId: 'Nach Elementkennung',
diff --git a/plugins/link/lang/el.js b/plugins/link/lang/el.js
index 1985ae181b7..88c3f3ac559 100644
--- a/plugins/link/lang/el.js
+++ b/plugins/link/lang/el.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'el', {
 		title: 'Ιδιότητες άγκυρας',
 		name: 'Όνομα άγκυρας',
 		errorName: 'Παρακαλούμε εισάγετε όνομα άγκυρας',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Αφαίρεση Άγκυρας'
 	},
 	anchorId: 'Βάσει του Element Id',
diff --git a/plugins/link/lang/en-au.js b/plugins/link/lang/en-au.js
index 757af937c2f..9306a841321 100644
--- a/plugins/link/lang/en-au.js
+++ b/plugins/link/lang/en-au.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'en-au', {
 		title: 'Anchor Properties',
 		name: 'Anchor Name',
 		errorName: 'Please type the anchor name',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'By Element Id',
diff --git a/plugins/link/lang/en-ca.js b/plugins/link/lang/en-ca.js
index 0018cbbe941..707b20c2217 100644
--- a/plugins/link/lang/en-ca.js
+++ b/plugins/link/lang/en-ca.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'en-ca', {
 		title: 'Anchor Properties',
 		name: 'Anchor Name',
 		errorName: 'Please type the anchor name',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'By Element Id',
diff --git a/plugins/link/lang/en-gb.js b/plugins/link/lang/en-gb.js
index f6b8dd2842b..b28bb344443 100644
--- a/plugins/link/lang/en-gb.js
+++ b/plugins/link/lang/en-gb.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'en-gb', {
 		title: 'Anchor Properties',
 		name: 'Anchor Name',
 		errorName: 'Please type the anchor name',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'By Element Id',
diff --git a/plugins/link/lang/en.js b/plugins/link/lang/en.js
index 2efc05ddaf9..23b4e95e2d9 100644
--- a/plugins/link/lang/en.js
+++ b/plugins/link/lang/en.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'en', {
 		title: 'Anchor Properties',
 		name: 'Anchor Name',
 		errorName: 'Please type the anchor name',
+		errorWhitespace: 'Anchor name cannot contain space characters',
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'By Element Id',
diff --git a/plugins/link/lang/eo.js b/plugins/link/lang/eo.js
index 0a75efa2cbd..21e696b5418 100644
--- a/plugins/link/lang/eo.js
+++ b/plugins/link/lang/eo.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'eo', {
 		title: 'Ankraj Atributoj',
 		name: 'Ankra Nomo',
 		errorName: 'Bv entajpi la ankran nomon',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Forigi Ankron'
 	},
 	anchorId: 'Per Elementidentigilo',
diff --git a/plugins/link/lang/es-mx.js b/plugins/link/lang/es-mx.js
index 1f00de52d94..bd75c2216bb 100644
--- a/plugins/link/lang/es-mx.js
+++ b/plugins/link/lang/es-mx.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'es-mx', {
 		title: 'Propiedades del ancla',
 		name: 'Nombre del ancla',
 		errorName: 'Escriba el nombre del ancla',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remover ancla'
 	},
 	anchorId: 'Por Id del elemento',
diff --git a/plugins/link/lang/es.js b/plugins/link/lang/es.js
index 8e1a7d14645..ff396cb401b 100644
--- a/plugins/link/lang/es.js
+++ b/plugins/link/lang/es.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'es', {
 		title: 'Propiedades de Referencia',
 		name: 'Nombre de la Referencia',
 		errorName: 'Por favor, complete el nombre de la Referencia',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Quitar Referencia'
 	},
 	anchorId: 'Por ID de elemento',
diff --git a/plugins/link/lang/et.js b/plugins/link/lang/et.js
index b880c5549b3..26461d6db91 100644
--- a/plugins/link/lang/et.js
+++ b/plugins/link/lang/et.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'et', {
 		title: 'Ankru omadused',
 		name: 'Ankru nimi',
 		errorName: 'Palun sisesta ankru nimi',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Eemalda ankur'
 	},
 	anchorId: 'Elemendi id järgi',
diff --git a/plugins/link/lang/eu.js b/plugins/link/lang/eu.js
index e4d94350b56..6ff490fb52b 100644
--- a/plugins/link/lang/eu.js
+++ b/plugins/link/lang/eu.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'eu', {
 		title: 'Ainguraren propietateak',
 		name: 'Ainguraren izena',
 		errorName: 'Idatzi ainguraren izena',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Kendu aingura'
 	},
 	anchorId: 'Elementuaren Id-aren arabera',
diff --git a/plugins/link/lang/fa.js b/plugins/link/lang/fa.js
index 45b713df949..7b1423f0961 100644
--- a/plugins/link/lang/fa.js
+++ b/plugins/link/lang/fa.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'fa', {
 		title: 'ویژگی​های لینک',
 		name: 'نام لینک',
 		errorName: 'لطفا نام لنگر را بنویسید',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'حذف لینک'
 	},
 	anchorId: 'با شناسهٴ المان',
diff --git a/plugins/link/lang/fi.js b/plugins/link/lang/fi.js
index 48b3682b026..b109ad242be 100644
--- a/plugins/link/lang/fi.js
+++ b/plugins/link/lang/fi.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'fi', {
 		title: 'Ankkurin ominaisuudet',
 		name: 'Nimi',
 		errorName: 'Ankkurille on kirjoitettava nimi',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Poista ankkuri'
 	},
 	anchorId: 'Ankkurin ID:n mukaan',
diff --git a/plugins/link/lang/fo.js b/plugins/link/lang/fo.js
index 0981828de8d..cb6b8facc14 100644
--- a/plugins/link/lang/fo.js
+++ b/plugins/link/lang/fo.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'fo', {
 		title: 'Eginleikar fyri marknastein',
 		name: 'Heiti marknasteinsins',
 		errorName: 'Vinarliga rita marknasteinsins heiti',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Strika marknastein'
 	},
 	anchorId: 'Eftir element Id',
diff --git a/plugins/link/lang/fr-ca.js b/plugins/link/lang/fr-ca.js
index 56a2c492cbb..2895eeaa66e 100644
--- a/plugins/link/lang/fr-ca.js
+++ b/plugins/link/lang/fr-ca.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'fr-ca', {
 		title: 'Propriétés de l\'ancre',
 		name: 'Nom de l\'ancre',
 		errorName: 'Veuillez saisir le nom de l\'ancre',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Supprimer l\'ancre'
 	},
 	anchorId: 'Par ID',
diff --git a/plugins/link/lang/fr.js b/plugins/link/lang/fr.js
index 62583abe4e2..102a4fdc436 100644
--- a/plugins/link/lang/fr.js
+++ b/plugins/link/lang/fr.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'fr', {
 		title: 'Propriétés de l\'ancre',
 		name: 'Nom de l\'ancre',
 		errorName: 'Veuillez entrer le nom de l\'ancre.',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Supprimer l\'ancre'
 	},
 	anchorId: 'Par ID d\'élément',
diff --git a/plugins/link/lang/gl.js b/plugins/link/lang/gl.js
index cd4cccff7a5..8fa886e1cbd 100644
--- a/plugins/link/lang/gl.js
+++ b/plugins/link/lang/gl.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'gl', {
 		title: 'Propiedades da ancoraxe',
 		name: 'Nome da ancoraxe',
 		errorName: 'Escriba o nome da ancoraxe',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Retirar a ancoraxe'
 	},
 	anchorId: 'Polo ID do elemento',
diff --git a/plugins/link/lang/gu.js b/plugins/link/lang/gu.js
index 6c35dde971e..f180e1f526a 100644
--- a/plugins/link/lang/gu.js
+++ b/plugins/link/lang/gu.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'gu', {
 		title: 'ઍંકરના ગુણ',
 		name: 'ઍંકરનું નામ',
 		errorName: 'ઍંકરનું નામ ટાઈપ કરો',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'સ્થિર નકરવું'
 	},
 	anchorId: 'ઍંકર એલિમન્ટ Id થી પસંદ કરો',
diff --git a/plugins/link/lang/he.js b/plugins/link/lang/he.js
index 8d0f459bf14..a914fbcdda9 100644
--- a/plugins/link/lang/he.js
+++ b/plugins/link/lang/he.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'he', {
 		title: 'מאפייני נקודת עיגון',
 		name: 'שם לנקודת עיגון',
 		errorName: 'יש להקליד שם לנקודת עיגון',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'מחיקת נקודת עיגון'
 	},
 	anchorId: 'עפ"י זיהוי (ID) האלמנט',
diff --git a/plugins/link/lang/hi.js b/plugins/link/lang/hi.js
index a6c46c5e611..74e9712719a 100644
--- a/plugins/link/lang/hi.js
+++ b/plugins/link/lang/hi.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'hi', {
 		title: 'ऐंकर प्रॉपर्टीज़',
 		name: 'ऐंकर का नाम',
 		errorName: 'ऐंकर का नाम टाइप करें',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'ऍलीमॅन्ट Id से',
diff --git a/plugins/link/lang/hr.js b/plugins/link/lang/hr.js
index 8da308fd0ce..10418d0ab77 100644
--- a/plugins/link/lang/hr.js
+++ b/plugins/link/lang/hr.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'hr', {
 		title: 'Svojstva sidra',
 		name: 'Ime sidra',
 		errorName: 'Molimo unesite ime sidra',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Ukloni sidro'
 	},
 	anchorId: 'Po Id elementa',
diff --git a/plugins/link/lang/hu.js b/plugins/link/lang/hu.js
index a5a16330a46..a7cc15f3f88 100644
--- a/plugins/link/lang/hu.js
+++ b/plugins/link/lang/hu.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'hu', {
 		title: 'Horgony tulajdonságai',
 		name: 'Horgony neve',
 		errorName: 'Kérem adja meg a horgony nevét',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Horgony eltávolítása'
 	},
 	anchorId: 'Azonosító szerint',
diff --git a/plugins/link/lang/id.js b/plugins/link/lang/id.js
index fa264a80749..6bd879c1e66 100644
--- a/plugins/link/lang/id.js
+++ b/plugins/link/lang/id.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'id', {
 		title: 'Anchor Properties', // MISSING
 		name: 'Anchor Name', // MISSING
 		errorName: 'Please type the anchor name', // MISSING
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor' // MISSING
 	},
 	anchorId: 'By Element Id', // MISSING
diff --git a/plugins/link/lang/is.js b/plugins/link/lang/is.js
index e04558c1b7c..32bae9273f0 100644
--- a/plugins/link/lang/is.js
+++ b/plugins/link/lang/is.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'is', {
 		title: 'Eigindi kaflamerkis',
 		name: 'Nafn bókamerkis',
 		errorName: 'Sláðu inn nafn bókamerkis!',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'Eftir auðkenni einingar',
diff --git a/plugins/link/lang/it.js b/plugins/link/lang/it.js
index 271eb71e921..41108405bd0 100644
--- a/plugins/link/lang/it.js
+++ b/plugins/link/lang/it.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'it', {
 		title: 'Proprietà ancora',
 		name: 'Nome ancora',
 		errorName: 'Inserici il nome dell\'ancora',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Rimuovi l\'ancora'
 	},
 	anchorId: 'Per id elemento',
diff --git a/plugins/link/lang/ja.js b/plugins/link/lang/ja.js
index 02802d4d088..005fa1d0dc4 100644
--- a/plugins/link/lang/ja.js
+++ b/plugins/link/lang/ja.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'ja', {
 		title: 'アンカーのプロパティ',
 		name: 'アンカー名',
 		errorName: 'アンカー名を入力してください。',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'アンカーを削除'
 	},
 	anchorId: 'エレメントID',
diff --git a/plugins/link/lang/ka.js b/plugins/link/lang/ka.js
index f886af263da..8c76b810f0b 100644
--- a/plugins/link/lang/ka.js
+++ b/plugins/link/lang/ka.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'ka', {
 		title: 'ღუზის პარამეტრები',
 		name: 'ღუზუს სახელი',
 		errorName: 'აკრიფეთ ღუზის სახელი',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'ელემენტის Id-თ',
diff --git a/plugins/link/lang/km.js b/plugins/link/lang/km.js
index 2fb4dae785c..9427e0b205b 100644
--- a/plugins/link/lang/km.js
+++ b/plugins/link/lang/km.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'km', {
 		title: 'លក្ខណៈ​យុថ្កា',
 		name: 'ឈ្មោះ​យុថ្កា',
 		errorName: 'សូម​បញ្ចូល​ឈ្មោះ​យុថ្កា',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'ដក​យុថ្កា​ចេញ'
 	},
 	anchorId: 'តាម ID ធាតុ',
diff --git a/plugins/link/lang/ko.js b/plugins/link/lang/ko.js
index 3ae651f6780..43638b15c53 100644
--- a/plugins/link/lang/ko.js
+++ b/plugins/link/lang/ko.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'ko', {
 		title: '책갈피 속성',
 		name: '책갈피 이름',
 		errorName: '책갈피 이름을 입력하십시오',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: '책갈피 제거'
 	},
 	anchorId: '책갈피 ID',
diff --git a/plugins/link/lang/ku.js b/plugins/link/lang/ku.js
index a37e673fc59..fc6f1c6a5b8 100644
--- a/plugins/link/lang/ku.js
+++ b/plugins/link/lang/ku.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'ku', {
 		title: 'خاسیەتی لەنگەر',
 		name: 'ناوی لەنگەر',
 		errorName: 'تکایه ناوی لەنگەر بنووسه',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'لابردنی لەنگەر'
 	},
 	anchorId: 'بەپێی ناسنامەی توخم',
diff --git a/plugins/link/lang/lt.js b/plugins/link/lang/lt.js
index 9fd9a035efe..cd2d88d69d5 100644
--- a/plugins/link/lang/lt.js
+++ b/plugins/link/lang/lt.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'lt', {
 		title: 'Žymės savybės',
 		name: 'Žymės vardas',
 		errorName: 'Prašome įvesti žymės vardą',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Pašalinti žymę'
 	},
 	anchorId: 'Pagal žymės Id',
diff --git a/plugins/link/lang/lv.js b/plugins/link/lang/lv.js
index cbfae66935f..51c13a5e418 100644
--- a/plugins/link/lang/lv.js
+++ b/plugins/link/lang/lv.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'lv', {
 		title: 'Iezīmes uzstādījumi',
 		name: 'Iezīmes nosaukums',
 		errorName: 'Lūdzu norādiet iezīmes nosaukumu',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Noņemt iezīmi'
 	},
 	anchorId: 'Pēc elementa ID',
diff --git a/plugins/link/lang/mk.js b/plugins/link/lang/mk.js
index c48c848f462..6f38fc11f85 100644
--- a/plugins/link/lang/mk.js
+++ b/plugins/link/lang/mk.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'mk', {
 		title: 'Anchor Properties',
 		name: 'Anchor Name',
 		errorName: 'Please type the anchor name',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'By Element Id', // MISSING
diff --git a/plugins/link/lang/mn.js b/plugins/link/lang/mn.js
index 6a8d8b7fbd1..8ab28a5bc6c 100644
--- a/plugins/link/lang/mn.js
+++ b/plugins/link/lang/mn.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'mn', {
 		title: 'Зангуугийн шинж чанар',
 		name: 'Зангуугийн нэр',
 		errorName: 'Зангуугийн нэрийг оруулна уу',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Зангууг устгах'
 	},
 	anchorId: 'Элемэнтйн Id нэрээр',
diff --git a/plugins/link/lang/ms.js b/plugins/link/lang/ms.js
index 2911ff224cf..01fdf6204b1 100644
--- a/plugins/link/lang/ms.js
+++ b/plugins/link/lang/ms.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'ms', {
 		title: 'Ciri-ciri Pautan',
 		name: 'Nama Pautan',
 		errorName: 'Sila taip nama pautan',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'dengan menggunakan ID elemen',
diff --git a/plugins/link/lang/nb.js b/plugins/link/lang/nb.js
index ca145df83e7..0fe798443f6 100644
--- a/plugins/link/lang/nb.js
+++ b/plugins/link/lang/nb.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'nb', {
 		title: 'Egenskaper for anker',
 		name: 'Ankernavn',
 		errorName: 'Vennligst skriv inn ankernavnet',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Fjern anker'
 	},
 	anchorId: 'Element etter ID',
diff --git a/plugins/link/lang/nl.js b/plugins/link/lang/nl.js
index 0b6b93730ad..5227d52da02 100644
--- a/plugins/link/lang/nl.js
+++ b/plugins/link/lang/nl.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'nl', {
 		title: 'Eigenschappen interne link',
 		name: 'Naam interne link',
 		errorName: 'Geef de naam van de interne link op',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Interne link verwijderen'
 	},
 	anchorId: 'Op kenmerk interne link',
diff --git a/plugins/link/lang/no.js b/plugins/link/lang/no.js
index 8d7359ea217..fb57acf4ab5 100644
--- a/plugins/link/lang/no.js
+++ b/plugins/link/lang/no.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'no', {
 		title: 'Egenskaper for anker',
 		name: 'Ankernavn',
 		errorName: 'Vennligst skriv inn ankernavnet',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Fjern anker'
 	},
 	anchorId: 'Element etter ID',
diff --git a/plugins/link/lang/oc.js b/plugins/link/lang/oc.js
index 82330c12e9e..77aae466eab 100644
--- a/plugins/link/lang/oc.js
+++ b/plugins/link/lang/oc.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'oc', {
 		title: 'Proprietats de l\'ancòra',
 		name: 'Nom de l\'ancòra',
 		errorName: 'Entratz lo nom de l\'ancòra',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Suprimir l\'ancòra'
 	},
 	anchorId: 'Per ID d\'element',
diff --git a/plugins/link/lang/pl.js b/plugins/link/lang/pl.js
index c45c3a2938c..1f9256f4da9 100644
--- a/plugins/link/lang/pl.js
+++ b/plugins/link/lang/pl.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'pl', {
 		title: 'Właściwości kotwicy',
 		name: 'Nazwa kotwicy',
 		errorName: 'Podaj nazwę kotwicy.',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Usuń kotwicę'
 	},
 	anchorId: 'Wg identyfikatora',
diff --git a/plugins/link/lang/pt-br.js b/plugins/link/lang/pt-br.js
index 391de881e37..d902f39cb32 100644
--- a/plugins/link/lang/pt-br.js
+++ b/plugins/link/lang/pt-br.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'pt-br', {
 		title: 'Formatar Âncora',
 		name: 'Nome da Âncora',
 		errorName: 'Por favor, digite o nome da âncora',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remover Âncora'
 	},
 	anchorId: 'Id da âncora',
diff --git a/plugins/link/lang/pt.js b/plugins/link/lang/pt.js
index fd3fa28bc3f..851fc4d8c0f 100644
--- a/plugins/link/lang/pt.js
+++ b/plugins/link/lang/pt.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'pt', {
 		title: 'Propriedades da âncora',
 		name: 'Nome da âncora',
 		errorName: 'Por favor, introduza o nome da âncora',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remover âncora'
 	},
 	anchorId: 'Por ID do elemento',
diff --git a/plugins/link/lang/ro.js b/plugins/link/lang/ro.js
index 81d27f79bde..4fd40634c8a 100644
--- a/plugins/link/lang/ro.js
+++ b/plugins/link/lang/ro.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'ro', {
 		title: 'Proprietăţi ancoră',
 		name: 'Numele ancorei',
 		errorName: 'Vă rugăm scrieţi numele ancorei',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Elimină ancora'
 	},
 	anchorId: 'după Id-ul elementului',
diff --git a/plugins/link/lang/ru.js b/plugins/link/lang/ru.js
index d8a48378ce8..07fc7ad3ac3 100644
--- a/plugins/link/lang/ru.js
+++ b/plugins/link/lang/ru.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'ru', {
 		title: 'Свойства якоря',
 		name: 'Имя якоря',
 		errorName: 'Пожалуйста, введите имя якоря',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Удалить якорь'
 	},
 	anchorId: 'По идентификатору',
diff --git a/plugins/link/lang/si.js b/plugins/link/lang/si.js
index 2fc73a5c0a6..0b7b5feaa37 100644
--- a/plugins/link/lang/si.js
+++ b/plugins/link/lang/si.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'si', {
 		title: 'ආධාරක ',
 		name: 'ආධාරකයේ නාමය',
 		errorName: 'කරුණාකර ආධාරකයේ නාමය ඇතුල් කරන්න',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'ආධාරකය ඉවත් කිරීම'
 	},
 	anchorId: 'By Element Id', // MISSING
diff --git a/plugins/link/lang/sk.js b/plugins/link/lang/sk.js
index e3367774947..444c6fa3907 100644
--- a/plugins/link/lang/sk.js
+++ b/plugins/link/lang/sk.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'sk', {
 		title: 'Vlastnosti kotvy',
 		name: 'Názov kotvy',
 		errorName: 'Zadajte prosím názov kotvy',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Odstrániť kotvu'
 	},
 	anchorId: 'Podľa Id objektu',
diff --git a/plugins/link/lang/sl.js b/plugins/link/lang/sl.js
index 13e2a0d248b..12a5ff1b629 100644
--- a/plugins/link/lang/sl.js
+++ b/plugins/link/lang/sl.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'sl', {
 		title: 'Lastnosti sidra',
 		name: 'Ime sidra',
 		errorName: 'Prosimo, vnesite ime sidra',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Odstrani sidro'
 	},
 	anchorId: 'Po ID-ju elementa',
diff --git a/plugins/link/lang/sq.js b/plugins/link/lang/sq.js
index 6bbec6dd7d4..e5e67158c27 100644
--- a/plugins/link/lang/sq.js
+++ b/plugins/link/lang/sq.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'sq', {
 		title: 'Karakteristikat e Spirancës',
 		name: 'Emri i Spirancës',
 		errorName: 'Ju lutemi shkruani emrin e spirancës',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Largo Spirancën'
 	},
 	anchorId: 'Sipas ID-së së Elementit',
diff --git a/plugins/link/lang/sr-latn.js b/plugins/link/lang/sr-latn.js
index ab9f8b7aa37..1e624950cfb 100644
--- a/plugins/link/lang/sr-latn.js
+++ b/plugins/link/lang/sr-latn.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'sr-latn', {
 		title: 'Karakteristike sidra',
 		name: 'Naziv sidra',
 		errorName: 'Unesite naziv sidra',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Ukloni sidro'
 	},
 	anchorId: 'Po Id-u elementa',
diff --git a/plugins/link/lang/sr.js b/plugins/link/lang/sr.js
index 3b565e2449c..83134826616 100644
--- a/plugins/link/lang/sr.js
+++ b/plugins/link/lang/sr.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'sr', {
 		title: 'Карактеристике сидра',
 		name: 'Назив сидра',
 		errorName: 'Унесите назив сидра',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Уклони сидро'
 	},
 	anchorId: 'Пo Ид-у елемента',
diff --git a/plugins/link/lang/sv.js b/plugins/link/lang/sv.js
index 22ec4136fb2..c0b3d75caf2 100644
--- a/plugins/link/lang/sv.js
+++ b/plugins/link/lang/sv.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'sv', {
 		title: 'Egenskaper för ankarlänk',
 		name: 'Ankarnamn',
 		errorName: 'Var god ange ett ankarnamn',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Radera ankare'
 	},
 	anchorId: 'Efter element-id',
diff --git a/plugins/link/lang/th.js b/plugins/link/lang/th.js
index 7047b61fddd..7f99dfa3c41 100644
--- a/plugins/link/lang/th.js
+++ b/plugins/link/lang/th.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'th', {
 		title: 'รายละเอียด Anchor',
 		name: 'ชื่อ Anchor',
 		errorName: 'กรุณาระบุชื่อของ Anchor',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Remove Anchor'
 	},
 	anchorId: 'ไอดี',
diff --git a/plugins/link/lang/tr.js b/plugins/link/lang/tr.js
index 30308dbc3f0..72efafdec6d 100644
--- a/plugins/link/lang/tr.js
+++ b/plugins/link/lang/tr.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'tr', {
 		title: 'Bağlantı Özellikleri',
 		name: 'Bağlantı Adı',
 		errorName: 'Lütfen bağlantı için ad giriniz',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Bağlantıyı Kaldır'
 	},
 	anchorId: 'Eleman Kimlik Numarası ile',
diff --git a/plugins/link/lang/tt.js b/plugins/link/lang/tt.js
index 6dec1df8b0d..64c0d472f0d 100644
--- a/plugins/link/lang/tt.js
+++ b/plugins/link/lang/tt.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'tt', {
 		title: 'Якорь үзлекләре',
 		name: 'Якорь исеме',
 		errorName: 'Якорьнең исемен языгыз',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Якорьне бетерү'
 	},
 	anchorId: 'Элемент идентификаторы буенча',
diff --git a/plugins/link/lang/ug.js b/plugins/link/lang/ug.js
index f52d3d4aee0..87b4ad0080f 100644
--- a/plugins/link/lang/ug.js
+++ b/plugins/link/lang/ug.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'ug', {
 		title: 'لەڭگەرلىك نۇقتا ئۇلانما خاسلىقى',
 		name: 'لەڭگەرلىك نۇقتا ئاتى',
 		errorName: 'لەڭگەرلىك نۇقتا ئاتىنى كىرگۈزۈڭ',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'لەڭگەرلىك نۇقتا ئۆچۈر'
 	},
 	anchorId: 'لەڭگەرلىك نۇقتا ID سى بويىچە',
diff --git a/plugins/link/lang/uk.js b/plugins/link/lang/uk.js
index 3889b8b9f03..7cae72752d7 100644
--- a/plugins/link/lang/uk.js
+++ b/plugins/link/lang/uk.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'uk', {
 		title: 'Властивості якоря',
 		name: 'Ім\'я якоря',
 		errorName: 'Будь ласка, вкажіть ім\'я якоря',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Прибрати якір'
 	},
 	anchorId: 'За ідентифікатором елементу',
diff --git a/plugins/link/lang/vi.js b/plugins/link/lang/vi.js
index c0dfabc7114..4177a3d51cd 100644
--- a/plugins/link/lang/vi.js
+++ b/plugins/link/lang/vi.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'vi', {
 		title: 'Thuộc tính điểm neo',
 		name: 'Tên của điểm neo',
 		errorName: 'Hãy nhập vào tên của điểm neo',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: 'Xóa neo'
 	},
 	anchorId: 'Theo định danh thành phần',
diff --git a/plugins/link/lang/zh-cn.js b/plugins/link/lang/zh-cn.js
index d3b25febe8c..b94f16f067d 100644
--- a/plugins/link/lang/zh-cn.js
+++ b/plugins/link/lang/zh-cn.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'zh-cn', {
 		title: '锚点链接属性',
 		name: '锚点名称',
 		errorName: '请输入锚点名称',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: '删除锚点'
 	},
 	anchorId: '按锚点 ID',
diff --git a/plugins/link/lang/zh.js b/plugins/link/lang/zh.js
index 86ec5402f89..21dbd2722e0 100644
--- a/plugins/link/lang/zh.js
+++ b/plugins/link/lang/zh.js
@@ -13,6 +13,7 @@ CKEDITOR.plugins.setLang( 'link', 'zh', {
 		title: '錨點內容',
 		name: '錨點名稱',
 		errorName: '請輸入錨點名稱',
+		errorWhitespace: 'Anchor name cannot contain space characters', // MISSING
 		remove: '移除錨點'
 	},
 	anchorId: '依元件編號',
diff --git a/tests/plugins/link/anchor.js b/tests/plugins/link/anchor.js
index 774ff76f056..fefb8d36653 100644
--- a/tests/plugins/link/anchor.js
+++ b/tests/plugins/link/anchor.js
@@ -207,6 +207,60 @@
 
 				assert.beautified.html( expected, editor.getData(), 'Prevent duplicated anchors failed in the ordered list with styled word' );
 			} );
+		},
+		// (#5305)
+		'test prevent adding anchor with SPACE character': function() {
+			assertWhitespaceAnchor( this.editorBot, '\u0020', 'SPACE' );
+		},
+
+		// (#5305)
+		'test prevent adding anchor with CHARACTER TABULATION character': function() {
+			assertWhitespaceAnchor( this.editorBot, '\u0009', 'CHARACTER TABULATION' );
+		},
+
+		// (#5305)
+		'test prevent adding anchor with FORM FEED character': function() {
+			assertWhitespaceAnchor( this.editorBot, '\u000c', 'FORM FEED' );
+		},
+
+		// (#5305)
+		'test add anchor with non-breaking space': function() {
+			var bot = this.editorBot,
+				windowStub = sinon.stub( window, 'alert' ),
+				template = '[<p>Simple text</p>]';
+
+			windowStub.restore();
+
+			bot.setHtmlWithSelection( template );
+			bot.dialog( 'anchor', function( dialog ) {
+				dialog.setValueOf( 'info', 'txtName', 'Foo\u00a0bar' );
+				dialog.getButton( 'ok' ).click();
+
+				assert.areEqual( 0, windowStub.callCount );
+			} );
 		}
 	} );
+
+	function assertWhitespaceAnchor( bot, unicode, name ) {
+		var windowStub = sinon.stub( window, 'alert' );
+
+		bot.dialog( 'anchor', function( dialog ) {
+
+			dialog.setValueOf( 'info', 'txtName', 'Foo' + unicode + 'bar' );
+			dialog.getButton( 'ok' ).click();
+
+			resume( function() {
+				windowStub.restore();
+
+				assert.areEqual( 1, windowStub.callCount );
+				assert.areEqual(
+					bot.editor.lang.link.anchor.errorWhitespace,
+					windowStub.args[ 0 ][ 0 ],
+					'Anchor containing' + name + 'space should not be added'
+				);
+			}, 10 );
+
+			wait();
+		} );
+	}
 }() );
diff --git a/tests/plugins/link/manual/anchorwithspace.html b/tests/plugins/link/manual/anchorwithspace.html
new file mode 100644
index 00000000000..202ca19147b
--- /dev/null
+++ b/tests/plugins/link/manual/anchorwithspace.html
@@ -0,0 +1,27 @@
+<h2><code>Iframe</code>-based editor</h2>
+<div id="iframe">
+	<p>Foo</p>
+</div>
+
+<h2><code>Div</code>-based editor</h2>
+<div id="div">
+	<p>Foo</p>
+</div>
+
+<h2>Inline editor</h2>
+<div id="inline" contenteditable="true">
+	<p>Foo</p>
+</div>
+
+<script>
+	CKEDITOR.replace( 'iframe', {
+		language: 'en'
+	} );
+	CKEDITOR.replace( 'div', {
+		extraPlugins: 'divarea',
+		language: 'en'
+	} );
+	CKEDITOR.inline( 'inline', {
+		language: 'en'
+	} );
+</script>
diff --git a/tests/plugins/link/manual/anchorwithspace.md b/tests/plugins/link/manual/anchorwithspace.md
new file mode 100644
index 00000000000..b4dbeae970a
--- /dev/null
+++ b/tests/plugins/link/manual/anchorwithspace.md
@@ -0,0 +1,10 @@
+@bender-tags: 4.20.1, bug, 5305
+@bender-ui: collapsed
+@bender-ckeditor-plugins: link, toolbar, wysiwygarea, floatingspace
+
+1. Open anchor dialog.
+2. Try to add an anchor that contains a space eg. `Foo bar`.
+
+**Expected:** Alert popups with the information: `Anchor name cannot contain space characters`.
+
+**Unexpected:** Anchor was added to the editable.