diff --git a/client/package-lock.json b/client/package-lock.json
index ae00bd7a..2239bfba 100644
--- a/client/package-lock.json
+++ b/client/package-lock.json
@@ -12,7 +12,7 @@
         "dequal": "^2.0.3",
         "easymde": "^2.18.0",
         "history": "^5.3.0",
-        "i18next": "^23.11.5",
+        "i18next": "^23.12.2",
         "i18next-browser-languagedetector": "^8.0.0",
         "initials": "^3.1.2",
         "js-cookie": "^3.0.5",
@@ -30,7 +30,7 @@
         "react-datepicker": "^4.25.0",
         "react-dom": "^18.2.0",
         "react-dropzone": "^14.2.3",
-        "react-i18next": "^14.1.2",
+        "react-i18next": "^15.0.0",
         "react-input-mask": "^2.0.4",
         "react-markdown": "^8.0.7",
         "react-photoswipe-gallery": "^2.2.7",
@@ -2007,9 +2007,9 @@
       "integrity": "sha512-x/rqGMdzj+fWZvCOYForTghzbtqPDZ5gPwaoNGHdgDfF2QA/XZbCBp4Moo5scrkAMPhB7z26XM/AaHuIJdgauA=="
     },
     "node_modules/@babel/runtime": {
-      "version": "7.24.6",
-      "resolved": "https://registry.npmjs.org/@babel/runtime/-/runtime-7.24.6.tgz",
-      "integrity": "sha512-Ja18XcETdEl5mzzACGd+DKgaGJzPTCow7EglgwTmHdwokzDFYh/MHua6lU6DV/hjF2IaOJ4oX2nqnjG7RElKOw==",
+      "version": "7.24.8",
+      "resolved": "https://registry.npmjs.org/@babel/runtime/-/runtime-7.24.8.tgz",
+      "integrity": "sha512-5F7SDGs1T72ZczbRwbGO9lQi0NLjQxzl6i4lJxLxfW9U5UluCSyEJeniWvnhl3/euNiqQVbo8zruhsDfid0esA==",
       "dependencies": {
         "regenerator-runtime": "^0.14.0"
       },
@@ -11975,9 +11975,9 @@
       }
     },
     "node_modules/i18next": {
-      "version": "23.11.5",
-      "resolved": "https://registry.npmjs.org/i18next/-/i18next-23.11.5.tgz",
-      "integrity": "sha512-41pvpVbW9rhZPk5xjCX2TPJi2861LEig/YRhUkY+1FQ2IQPS0bKUDYnEqY8XPPbB48h1uIwLnP9iiEfuSl20CA==",
+      "version": "23.12.2",
+      "resolved": "https://registry.npmjs.org/i18next/-/i18next-23.12.2.tgz",
+      "integrity": "sha512-XIeh5V+bi8SJSWGL3jqbTEBW5oD6rbP5L+E7dVQh1MNTxxYef0x15rhJVcRb7oiuq4jLtgy2SD8eFlf6P2cmqg==",
       "funding": [
         {
           "type": "individual",
@@ -22084,11 +22084,11 @@
       "integrity": "sha512-nsO+KSNgo1SbJqJEYRE9ERzo7YtYbou/OqjSQKxV7jcKox7+usiUVZOAC+XnDOABXggQTno0Y1CpVnuWEc1boQ=="
     },
     "node_modules/react-i18next": {
-      "version": "14.1.2",
-      "resolved": "https://registry.npmjs.org/react-i18next/-/react-i18next-14.1.2.tgz",
-      "integrity": "sha512-FSIcJy6oauJbGEXfhUgVeLzvWBhIBIS+/9c6Lj4niwKZyGaGb4V4vUbATXSlsHJDXXB+ociNxqFNiFuV1gmoqg==",
+      "version": "15.0.0",
+      "resolved": "https://registry.npmjs.org/react-i18next/-/react-i18next-15.0.0.tgz",
+      "integrity": "sha512-2O3IgF4zivg57Q6p6i+ChDgJ371IDcEWbuWC6gvoh5NbkDMs0Q+O7RPr4v61+Se32E0V+LmtwePAeqWZW0bi6g==",
       "dependencies": {
-        "@babel/runtime": "^7.23.9",
+        "@babel/runtime": "^7.24.8",
         "html-parse-stringify": "^3.0.1"
       },
       "peerDependencies": {
diff --git a/client/package.json b/client/package.json
index 4d000f74..7e975a5f 100755
--- a/client/package.json
+++ b/client/package.json
@@ -65,7 +65,7 @@
     "dequal": "^2.0.3",
     "easymde": "^2.18.0",
     "history": "^5.3.0",
-    "i18next": "^23.11.5",
+    "i18next": "^23.12.2",
     "i18next-browser-languagedetector": "^8.0.0",
     "initials": "^3.1.2",
     "js-cookie": "^3.0.5",
@@ -83,7 +83,7 @@
     "react-datepicker": "^4.25.0",
     "react-dom": "^18.2.0",
     "react-dropzone": "^14.2.3",
-    "react-i18next": "^14.1.2",
+    "react-i18next": "^15.0.0",
     "react-input-mask": "^2.0.4",
     "react-markdown": "^8.0.7",
     "react-photoswipe-gallery": "^2.2.7",
diff --git a/client/src/i18n.js b/client/src/i18n.js
index 4f5dda56..26dae90d 100644
--- a/client/src/i18n.js
+++ b/client/src/i18n.js
@@ -58,9 +58,9 @@ i18n
   .use(initReactI18next)
   .init({
     resources: embeddedLocales,
-    fallbackLng: 'en',
+    fallbackLng: 'en-US',
     supportedLngs: languages,
-    load: 'languageOnly',
+    load: 'currentOnly',
     interpolation: {
       escapeValue: false,
       format(value, format, language) {
@@ -80,7 +80,7 @@ i18n
   });
 
 i18n.loadCoreLocale = async (language = i18n.resolvedLanguage) => {
-  if (language === 'en') {
+  if (language === i18n.options.fallbackLng[0]) {
     return;
   }
 
diff --git a/client/src/locales/bg/core.js b/client/src/locales/bg-BG/core.js
similarity index 100%
rename from client/src/locales/bg/core.js
rename to client/src/locales/bg-BG/core.js
diff --git a/client/src/locales/bg/index.js b/client/src/locales/bg-BG/index.js
similarity index 85%
rename from client/src/locales/bg/index.js
rename to client/src/locales/bg-BG/index.js
index 95c609bf..4b1631bf 100644
--- a/client/src/locales/bg/index.js
+++ b/client/src/locales/bg-BG/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'bg',
+  language: 'bg-BG',
   country: 'bg',
   name: 'Български',
   embeddedLocale: login,
diff --git a/client/src/locales/bg/login.js b/client/src/locales/bg-BG/login.js
similarity index 100%
rename from client/src/locales/bg/login.js
rename to client/src/locales/bg-BG/login.js
diff --git a/client/src/locales/cs/core.js b/client/src/locales/cs-CZ/core.js
similarity index 100%
rename from client/src/locales/cs/core.js
rename to client/src/locales/cs-CZ/core.js
diff --git a/client/src/locales/cs/index.js b/client/src/locales/cs-CZ/index.js
similarity index 84%
rename from client/src/locales/cs/index.js
rename to client/src/locales/cs-CZ/index.js
index b172ade8..a8380e7c 100644
--- a/client/src/locales/cs/index.js
+++ b/client/src/locales/cs-CZ/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'cs',
+  language: 'cs-CZ',
   country: 'cz',
   name: 'Čeština',
   embeddedLocale: login,
diff --git a/client/src/locales/cs/login.js b/client/src/locales/cs-CZ/login.js
similarity index 100%
rename from client/src/locales/cs/login.js
rename to client/src/locales/cs-CZ/login.js
diff --git a/client/src/locales/da/core.js b/client/src/locales/da-DK/core.js
similarity index 100%
rename from client/src/locales/da/core.js
rename to client/src/locales/da-DK/core.js
diff --git a/client/src/locales/da/index.js b/client/src/locales/da-DK/index.js
similarity index 83%
rename from client/src/locales/da/index.js
rename to client/src/locales/da-DK/index.js
index 9fcfa709..937f5ae4 100644
--- a/client/src/locales/da/index.js
+++ b/client/src/locales/da-DK/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'da',
+  language: 'da-DK',
   country: 'dk',
   name: 'Dansk',
   embeddedLocale: login,
diff --git a/client/src/locales/da/login.js b/client/src/locales/da-DK/login.js
similarity index 100%
rename from client/src/locales/da/login.js
rename to client/src/locales/da-DK/login.js
diff --git a/client/src/locales/de/core.js b/client/src/locales/de-DE/core.js
similarity index 100%
rename from client/src/locales/de/core.js
rename to client/src/locales/de-DE/core.js
diff --git a/client/src/locales/de/index.js b/client/src/locales/de-DE/index.js
similarity index 84%
rename from client/src/locales/de/index.js
rename to client/src/locales/de-DE/index.js
index fc655946..2eb9ea7b 100644
--- a/client/src/locales/de/index.js
+++ b/client/src/locales/de-DE/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'de',
+  language: 'de-DE',
   country: 'de',
   name: 'Deutsch',
   embeddedLocale: login,
diff --git a/client/src/locales/de/login.js b/client/src/locales/de-DE/login.js
similarity index 100%
rename from client/src/locales/de/login.js
rename to client/src/locales/de-DE/login.js
diff --git a/client/src/locales/en/core.js b/client/src/locales/en-US/core.js
similarity index 100%
rename from client/src/locales/en/core.js
rename to client/src/locales/en-US/core.js
diff --git a/client/src/locales/en/index.js b/client/src/locales/en-US/index.js
similarity index 81%
rename from client/src/locales/en/index.js
rename to client/src/locales/en-US/index.js
index 73cf0522..3aea6da7 100644
--- a/client/src/locales/en/index.js
+++ b/client/src/locales/en-US/index.js
@@ -4,8 +4,8 @@ import login from './login';
 import core from './core';
 
 export default {
-  language: 'en',
-  country: 'gb',
+  language: 'en-US',
+  country: 'us',
   name: 'English',
   embeddedLocale: merge(login, core),
 };
diff --git a/client/src/locales/en/login.js b/client/src/locales/en-US/login.js
similarity index 100%
rename from client/src/locales/en/login.js
rename to client/src/locales/en-US/login.js
diff --git a/client/src/locales/es/core.js b/client/src/locales/es-ES/core.js
similarity index 100%
rename from client/src/locales/es/core.js
rename to client/src/locales/es-ES/core.js
diff --git a/client/src/locales/es/index.js b/client/src/locales/es-ES/index.js
similarity index 84%
rename from client/src/locales/es/index.js
rename to client/src/locales/es-ES/index.js
index bda1fe81..d853b3df 100644
--- a/client/src/locales/es/index.js
+++ b/client/src/locales/es-ES/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'es',
+  language: 'es-ES',
   country: 'es',
   name: 'Español',
   embeddedLocale: login,
diff --git a/client/src/locales/es/login.js b/client/src/locales/es-ES/login.js
similarity index 100%
rename from client/src/locales/es/login.js
rename to client/src/locales/es-ES/login.js
diff --git a/client/src/locales/fa/core.js b/client/src/locales/fa-IR/core.js
similarity index 100%
rename from client/src/locales/fa/core.js
rename to client/src/locales/fa-IR/core.js
diff --git a/client/src/locales/fa/index.js b/client/src/locales/fa-IR/index.js
similarity index 84%
rename from client/src/locales/fa/index.js
rename to client/src/locales/fa-IR/index.js
index a03206be..62024311 100644
--- a/client/src/locales/fa/index.js
+++ b/client/src/locales/fa-IR/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'fa',
+  language: 'fa-IR',
   country: 'ir',
   name: 'فارسی',
   embeddedLocale: login,
diff --git a/client/src/locales/fa/login.js b/client/src/locales/fa-IR/login.js
similarity index 100%
rename from client/src/locales/fa/login.js
rename to client/src/locales/fa-IR/login.js
diff --git a/client/src/locales/fr/core.js b/client/src/locales/fr-FR/core.js
similarity index 100%
rename from client/src/locales/fr/core.js
rename to client/src/locales/fr-FR/core.js
diff --git a/client/src/locales/fr/index.js b/client/src/locales/fr-FR/index.js
similarity index 84%
rename from client/src/locales/fr/index.js
rename to client/src/locales/fr-FR/index.js
index 945c1bc3..58933341 100644
--- a/client/src/locales/fr/index.js
+++ b/client/src/locales/fr-FR/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'fr',
+  language: 'fr-FR',
   country: 'fr',
   name: 'Français',
   embeddedLocale: login,
diff --git a/client/src/locales/fr/login.js b/client/src/locales/fr-FR/login.js
similarity index 100%
rename from client/src/locales/fr/login.js
rename to client/src/locales/fr-FR/login.js
diff --git a/client/src/locales/hu/core.js b/client/src/locales/hu-HU/core.js
similarity index 100%
rename from client/src/locales/hu/core.js
rename to client/src/locales/hu-HU/core.js
diff --git a/client/src/locales/hu/index.js b/client/src/locales/hu-HU/index.js
similarity index 83%
rename from client/src/locales/hu/index.js
rename to client/src/locales/hu-HU/index.js
index 17e618ee..8b0ccdb5 100644
--- a/client/src/locales/hu/index.js
+++ b/client/src/locales/hu-HU/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'hu',
+  language: 'hu-HU',
   country: 'hu',
   name: 'Magyar',
   embeddedLocale: login,
diff --git a/client/src/locales/hu/login.js b/client/src/locales/hu-HU/login.js
similarity index 100%
rename from client/src/locales/hu/login.js
rename to client/src/locales/hu-HU/login.js
diff --git a/client/src/locales/id/core.js b/client/src/locales/id-ID/core.js
similarity index 100%
rename from client/src/locales/id/core.js
rename to client/src/locales/id-ID/core.js
diff --git a/client/src/locales/id/index.js b/client/src/locales/id-ID/index.js
similarity index 85%
rename from client/src/locales/id/index.js
rename to client/src/locales/id-ID/index.js
index 42801f31..e739c696 100644
--- a/client/src/locales/id/index.js
+++ b/client/src/locales/id-ID/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'id',
+  language: 'id-ID',
   country: 'id',
   name: 'Bahasa Indonesia',
   embeddedLocale: login,
diff --git a/client/src/locales/id/login.js b/client/src/locales/id-ID/login.js
similarity index 100%
rename from client/src/locales/id/login.js
rename to client/src/locales/id-ID/login.js
diff --git a/client/src/locales/index.js b/client/src/locales/index.js
index 3f8175eb..bcc7eea3 100644
--- a/client/src/locales/index.js
+++ b/client/src/locales/index.js
@@ -1,53 +1,53 @@
-import bg from './bg';
-import cs from './cs';
-import da from './da';
-import de from './de';
-import en from './en';
-import es from './es';
-import fa from './fa';
-import fr from './fr';
-import hu from './hu';
-import id from './id';
-import it from './it';
-import ja from './ja';
-import ko from './ko';
-import nl from './nl';
-import pl from './pl';
-import pt from './pt';
-import ro from './ro';
-import ru from './ru';
-import sk from './sk';
-import sv from './sv';
-import tr from './tr';
-import ua from './ua';
-import uz from './uz';
-import zh from './zh';
+import bgBG from './bg-BG';
+import csCZ from './cs-CZ';
+import daDK from './da-DK';
+import deDE from './de-DE';
+import enUS from './en-US';
+import esES from './es-ES';
+import faIR from './fa-IR';
+import frFR from './fr-FR';
+import huHU from './hu-HU';
+import idID from './id-ID';
+import itIT from './it-IT';
+import jaJP from './ja-JP';
+import koKR from './ko-KR';
+import nlNL from './nl-NL';
+import plPL from './pl-PL';
+import ptBR from './pt-BR';
+import roRO from './ro-RO';
+import ruRU from './ru-RU';
+import skSK from './sk-SK';
+import svSE from './sv-SE';
+import trTR from './tr-TR';
+import ukUA from './uk-UA';
+import uzUZ from './uz-UZ';
+import zhCN from './zh-CN';
 
 const locales = [
-  bg,
-  cs,
-  da,
-  de,
-  en,
-  es,
-  fa,
-  fr,
-  hu,
-  id,
-  it,
-  ja,
-  ko,
-  nl,
-  pl,
-  pt,
-  ro,
-  ru,
-  sk,
-  sv,
-  tr,
-  ua,
-  uz,
-  zh,
+  bgBG,
+  csCZ,
+  daDK,
+  deDE,
+  enUS,
+  esES,
+  faIR,
+  frFR,
+  huHU,
+  idID,
+  itIT,
+  jaJP,
+  koKR,
+  nlNL,
+  plPL,
+  ptBR,
+  roRO,
+  ruRU,
+  skSK,
+  svSE,
+  trTR,
+  ukUA,
+  uzUZ,
+  zhCN,
 ];
 
 export default locales;
diff --git a/client/src/locales/it/core.js b/client/src/locales/it-IT/core.js
similarity index 99%
rename from client/src/locales/it/core.js
rename to client/src/locales/it-IT/core.js
index 1afb8926..f503c6d0 100644
--- a/client/src/locales/it/core.js
+++ b/client/src/locales/it-IT/core.js
@@ -1,4 +1,8 @@
+import dateFns from 'date-fns/locale/it';
+
 export default {
+  dateFns,
+
   format: {
     date: 'd/M/yyyy',
     time: 'p',
diff --git a/client/src/locales/it/index.js b/client/src/locales/it-IT/index.js
similarity index 84%
rename from client/src/locales/it/index.js
rename to client/src/locales/it-IT/index.js
index bc01113b..8f64a9a6 100644
--- a/client/src/locales/it/index.js
+++ b/client/src/locales/it-IT/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'it',
+  language: 'it-IT',
   country: 'it',
   name: 'Italiano',
   embeddedLocale: login,
diff --git a/client/src/locales/it/login.js b/client/src/locales/it-IT/login.js
similarity index 100%
rename from client/src/locales/it/login.js
rename to client/src/locales/it-IT/login.js
diff --git a/client/src/locales/ja/core.js b/client/src/locales/ja-JP/core.js
similarity index 100%
rename from client/src/locales/ja/core.js
rename to client/src/locales/ja-JP/core.js
diff --git a/client/src/locales/ja/index.js b/client/src/locales/ja-JP/index.js
similarity index 84%
rename from client/src/locales/ja/index.js
rename to client/src/locales/ja-JP/index.js
index b33d7c46..a196e3ff 100644
--- a/client/src/locales/ja/index.js
+++ b/client/src/locales/ja-JP/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'ja',
+  language: 'ja-JP',
   country: 'jp',
   name: '日本語',
   embeddedLocale: login,
diff --git a/client/src/locales/ja/login.js b/client/src/locales/ja-JP/login.js
similarity index 100%
rename from client/src/locales/ja/login.js
rename to client/src/locales/ja-JP/login.js
diff --git a/client/src/locales/ko/core.js b/client/src/locales/ko-KR/core.js
similarity index 100%
rename from client/src/locales/ko/core.js
rename to client/src/locales/ko-KR/core.js
diff --git a/client/src/locales/ko/index.js b/client/src/locales/ko-KR/index.js
similarity index 84%
rename from client/src/locales/ko/index.js
rename to client/src/locales/ko-KR/index.js
index d0eb9bf0..55970aa5 100644
--- a/client/src/locales/ko/index.js
+++ b/client/src/locales/ko-KR/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'ko',
+  language: 'ko-KR',
   country: 'kr',
   name: '한국어',
   embeddedLocale: login,
diff --git a/client/src/locales/ko/login.js b/client/src/locales/ko-KR/login.js
similarity index 100%
rename from client/src/locales/ko/login.js
rename to client/src/locales/ko-KR/login.js
diff --git a/client/src/locales/nl/core.js b/client/src/locales/nl-NL/core.js
similarity index 100%
rename from client/src/locales/nl/core.js
rename to client/src/locales/nl-NL/core.js
diff --git a/client/src/locales/nl/index.js b/client/src/locales/nl-NL/index.js
similarity index 84%
rename from client/src/locales/nl/index.js
rename to client/src/locales/nl-NL/index.js
index 6e24c664..f7f03eb4 100644
--- a/client/src/locales/nl/index.js
+++ b/client/src/locales/nl-NL/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'nl',
+  language: 'nl-NL',
   country: 'nl',
   name: 'Nederlands',
   embeddedLocale: login,
diff --git a/client/src/locales/nl/login.js b/client/src/locales/nl-NL/login.js
similarity index 100%
rename from client/src/locales/nl/login.js
rename to client/src/locales/nl-NL/login.js
diff --git a/client/src/locales/pl/core.js b/client/src/locales/pl-PL/core.js
similarity index 100%
rename from client/src/locales/pl/core.js
rename to client/src/locales/pl-PL/core.js
diff --git a/client/src/locales/pl/index.js b/client/src/locales/pl-PL/index.js
similarity index 83%
rename from client/src/locales/pl/index.js
rename to client/src/locales/pl-PL/index.js
index 73a9a66b..33ab45c7 100644
--- a/client/src/locales/pl/index.js
+++ b/client/src/locales/pl-PL/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'pl',
+  language: 'pl-PL',
   country: 'pl',
   name: 'Polski',
   embeddedLocale: login,
diff --git a/client/src/locales/pl/login.js b/client/src/locales/pl-PL/login.js
similarity index 100%
rename from client/src/locales/pl/login.js
rename to client/src/locales/pl-PL/login.js
diff --git a/client/src/locales/pt/core.js b/client/src/locales/pt-BR/core.js
similarity index 100%
rename from client/src/locales/pt/core.js
rename to client/src/locales/pt-BR/core.js
diff --git a/client/src/locales/pt/index.js b/client/src/locales/pt-BR/index.js
similarity index 84%
rename from client/src/locales/pt/index.js
rename to client/src/locales/pt-BR/index.js
index b3c867f7..56bac4c7 100644
--- a/client/src/locales/pt/index.js
+++ b/client/src/locales/pt-BR/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'pt',
+  language: 'pt-BR',
   country: 'br',
   name: 'Português',
   embeddedLocale: login,
diff --git a/client/src/locales/pt/login.js b/client/src/locales/pt-BR/login.js
similarity index 100%
rename from client/src/locales/pt/login.js
rename to client/src/locales/pt-BR/login.js
diff --git a/client/src/locales/ro/core.js b/client/src/locales/ro-RO/core.js
similarity index 100%
rename from client/src/locales/ro/core.js
rename to client/src/locales/ro-RO/core.js
diff --git a/client/src/locales/ro/index.js b/client/src/locales/ro-RO/index.js
similarity index 84%
rename from client/src/locales/ro/index.js
rename to client/src/locales/ro-RO/index.js
index b10ed81d..b34d44ab 100644
--- a/client/src/locales/ro/index.js
+++ b/client/src/locales/ro-RO/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'ro',
+  language: 'ro-RO',
   country: 'ro',
   name: 'Română',
   embeddedLocale: login,
diff --git a/client/src/locales/ro/login.js b/client/src/locales/ro-RO/login.js
similarity index 100%
rename from client/src/locales/ro/login.js
rename to client/src/locales/ro-RO/login.js
diff --git a/client/src/locales/ru/core.js b/client/src/locales/ru-RU/core.js
similarity index 100%
rename from client/src/locales/ru/core.js
rename to client/src/locales/ru-RU/core.js
diff --git a/client/src/locales/ru/index.js b/client/src/locales/ru-RU/index.js
similarity index 84%
rename from client/src/locales/ru/index.js
rename to client/src/locales/ru-RU/index.js
index 1ffb7e0c..8c3b7914 100644
--- a/client/src/locales/ru/index.js
+++ b/client/src/locales/ru-RU/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'ru',
+  language: 'ru-RU',
   country: 'ru',
   name: 'Русский',
   embeddedLocale: login,
diff --git a/client/src/locales/ru/login.js b/client/src/locales/ru-RU/login.js
similarity index 100%
rename from client/src/locales/ru/login.js
rename to client/src/locales/ru-RU/login.js
diff --git a/client/src/locales/sk/core.js b/client/src/locales/sk-SK/core.js
similarity index 100%
rename from client/src/locales/sk/core.js
rename to client/src/locales/sk-SK/core.js
diff --git a/client/src/locales/sk/index.js b/client/src/locales/sk-SK/index.js
similarity index 84%
rename from client/src/locales/sk/index.js
rename to client/src/locales/sk-SK/index.js
index ad9c4046..3a0837b1 100644
--- a/client/src/locales/sk/index.js
+++ b/client/src/locales/sk-SK/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'sk',
+  language: 'sk-SK',
   country: 'sk',
   name: 'Slovenčina',
   embeddedLocale: login,
diff --git a/client/src/locales/sk/login.js b/client/src/locales/sk-SK/login.js
similarity index 100%
rename from client/src/locales/sk/login.js
rename to client/src/locales/sk-SK/login.js
diff --git a/client/src/locales/sv/core.js b/client/src/locales/sv-SE/core.js
similarity index 100%
rename from client/src/locales/sv/core.js
rename to client/src/locales/sv-SE/core.js
diff --git a/client/src/locales/sv/index.js b/client/src/locales/sv-SE/index.js
similarity index 84%
rename from client/src/locales/sv/index.js
rename to client/src/locales/sv-SE/index.js
index d3b043d0..d5459e59 100644
--- a/client/src/locales/sv/index.js
+++ b/client/src/locales/sv-SE/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'sv',
+  language: 'sv-SE',
   country: 'se',
   name: 'Svenska',
   embeddedLocale: login,
diff --git a/client/src/locales/sv/login.js b/client/src/locales/sv-SE/login.js
similarity index 100%
rename from client/src/locales/sv/login.js
rename to client/src/locales/sv-SE/login.js
diff --git a/client/src/locales/tr/core.js b/client/src/locales/tr-TR/core.js
similarity index 100%
rename from client/src/locales/tr/core.js
rename to client/src/locales/tr-TR/core.js
diff --git a/client/src/locales/tr/index.js b/client/src/locales/tr-TR/index.js
similarity index 84%
rename from client/src/locales/tr/index.js
rename to client/src/locales/tr-TR/index.js
index 5af65ff1..79e6c4ba 100644
--- a/client/src/locales/tr/index.js
+++ b/client/src/locales/tr-TR/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'tr',
+  language: 'tr-TR',
   country: 'tr',
   name: 'Türkçe',
   embeddedLocale: login,
diff --git a/client/src/locales/tr/login.js b/client/src/locales/tr-TR/login.js
similarity index 100%
rename from client/src/locales/tr/login.js
rename to client/src/locales/tr-TR/login.js
diff --git a/client/src/locales/ua/core.js b/client/src/locales/uk-UA/core.js
similarity index 99%
rename from client/src/locales/ua/core.js
rename to client/src/locales/uk-UA/core.js
index d1860325..eb3063a5 100644
--- a/client/src/locales/ua/core.js
+++ b/client/src/locales/uk-UA/core.js
@@ -1,4 +1,8 @@
+import dateFns from 'date-fns/locale/uk';
+
 export default {
+  dateFns,
+
   format: {
     date: 'd/M/yyyy',
     time: 'p',
diff --git a/client/src/locales/ua/index.js b/client/src/locales/uk-UA/index.js
similarity index 85%
rename from client/src/locales/ua/index.js
rename to client/src/locales/uk-UA/index.js
index 0190368d..1255afcb 100644
--- a/client/src/locales/ua/index.js
+++ b/client/src/locales/uk-UA/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'ua',
+  language: 'uk-UA',
   country: 'ua',
   name: 'Українська',
   embeddedLocale: login,
diff --git a/client/src/locales/ua/login.js b/client/src/locales/uk-UA/login.js
similarity index 100%
rename from client/src/locales/ua/login.js
rename to client/src/locales/uk-UA/login.js
diff --git a/client/src/locales/uz/core.js b/client/src/locales/uz-UZ/core.js
similarity index 99%
rename from client/src/locales/uz/core.js
rename to client/src/locales/uz-UZ/core.js
index 084de78e..f2d080c8 100644
--- a/client/src/locales/uz/core.js
+++ b/client/src/locales/uz-UZ/core.js
@@ -1,4 +1,8 @@
+import dateFns from 'date-fns/locale/uz';
+
 export default {
+  dateFns,
+
   format: {
     date: 'M/d/yyyy',
     time: 'p',
diff --git a/client/src/locales/uz/index.js b/client/src/locales/uz-UZ/index.js
similarity index 83%
rename from client/src/locales/uz/index.js
rename to client/src/locales/uz-UZ/index.js
index 6ecec3c6..a023b970 100644
--- a/client/src/locales/uz/index.js
+++ b/client/src/locales/uz-UZ/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'uz',
+  language: 'uz-UZ',
   country: 'uz',
   name: "O'zbek",
   embeddedLocale: login,
diff --git a/client/src/locales/uz/login.js b/client/src/locales/uz-UZ/login.js
similarity index 100%
rename from client/src/locales/uz/login.js
rename to client/src/locales/uz-UZ/login.js
diff --git a/client/src/locales/zh/core.js b/client/src/locales/zh-CN/core.js
similarity index 99%
rename from client/src/locales/zh/core.js
rename to client/src/locales/zh-CN/core.js
index 95ae46c3..58e03d86 100644
--- a/client/src/locales/zh/core.js
+++ b/client/src/locales/zh-CN/core.js
@@ -1,4 +1,8 @@
+import dateFns from 'date-fns/locale/zh-CN';
+
 export default {
+  dateFns,
+
   format: {
     date: 'M/d/yyyy',
     time: 'p',
diff --git a/client/src/locales/zh/index.js b/client/src/locales/zh-CN/index.js
similarity index 83%
rename from client/src/locales/zh/index.js
rename to client/src/locales/zh-CN/index.js
index aa5c15eb..892340e8 100644
--- a/client/src/locales/zh/index.js
+++ b/client/src/locales/zh-CN/index.js
@@ -1,7 +1,7 @@
 import login from './login';
 
 export default {
-  language: 'zh',
+  language: 'zh-CN',
   country: 'cn',
   name: '中文',
   embeddedLocale: login,
diff --git a/client/src/locales/zh/login.js b/client/src/locales/zh-CN/login.js
similarity index 100%
rename from client/src/locales/zh/login.js
rename to client/src/locales/zh-CN/login.js
diff --git a/server/api/controllers/users/create.js b/server/api/controllers/users/create.js
index d1dc4a68..dc76b31f 100755
--- a/server/api/controllers/users/create.js
+++ b/server/api/controllers/users/create.js
@@ -50,7 +50,7 @@ module.exports = {
     },
     language: {
       type: 'string',
-      isNotEmptyString: true,
+      isIn: User.LANGUAGES,
       allowNull: true,
     },
     subscribeToOwnCards: {
diff --git a/server/api/controllers/users/update.js b/server/api/controllers/users/update.js
index a8e6215e..a46a2f7f 100755
--- a/server/api/controllers/users/update.js
+++ b/server/api/controllers/users/update.js
@@ -36,7 +36,7 @@ module.exports = {
     },
     language: {
       type: 'string',
-      isNotEmptyString: true,
+      isIn: User.LANGUAGES,
       allowNull: true,
     },
     subscribeToOwnCards: {
diff --git a/server/api/models/User.js b/server/api/models/User.js
index 09034437..486a66b2 100755
--- a/server/api/models/User.js
+++ b/server/api/models/User.js
@@ -5,11 +5,39 @@
  * @docs        :: https://sailsjs.com/docs/concepts/models-and-orm/models
  */
 
+const LANGUAGES = [
+  'bg-BG',
+  'cs-CZ',
+  'da-DK',
+  'de-DE',
+  'en-US',
+  'es-ES',
+  'fa-IR',
+  'fr-FR',
+  'hu-HU',
+  'id-ID',
+  'it-IT',
+  'ja-JP',
+  'ko-KR',
+  'nl-NL',
+  'pl-PL',
+  'pt-BR',
+  'ro-RO',
+  'ru-RU',
+  'sk-SK',
+  'sv-SE',
+  'tr-TR',
+  'uk-UA',
+  'uz-UZ',
+  'zh-CN',
+];
+
 const OIDC = {
   id: '_oidc',
 };
 
 module.exports = {
+  LANGUAGES,
   OIDC,
 
   attributes: {
@@ -62,7 +90,7 @@ module.exports = {
     },
     language: {
       type: 'string',
-      isNotEmptyString: true,
+      isIn: LANGUAGES,
       allowNull: true,
     },
     subscribeToOwnCards: {
diff --git a/server/db/migrations/20220523131229_add_image_to_attachment_table.js b/server/db/migrations/20220523131229_add_image_to_attachment_table.js
index 989f6957..25d6f62f 100644
--- a/server/db/migrations/20220523131229_add_image_to_attachment_table.js
+++ b/server/db/migrations/20220523131229_add_image_to_attachment_table.js
@@ -15,7 +15,7 @@ module.exports.up = async (knex) => {
   const attachments = await knex('attachment');
 
   // eslint-disable-next-line no-restricted-syntax
-  for (attachment of attachments) {
+  for (const attachment of attachments) {
     if (attachment.is_image) {
       const image = sharp(
         path.join(config.custom.attachmentsPath, attachment.dirname, attachment.filename),
@@ -54,7 +54,7 @@ module.exports.down = async (knex) => {
   const attachments = await knex('attachment');
 
   // eslint-disable-next-line no-restricted-syntax
-  for (attachment of attachments) {
+  for (const attachment of attachments) {
     // eslint-disable-next-line no-await-in-loop
     await knex('attachment')
       .update({
diff --git a/server/db/migrations/20221223131625_preserve_original_format_of_images.js b/server/db/migrations/20221223131625_preserve_original_format_of_images.js
index de2ec07c..f78762d2 100644
--- a/server/db/migrations/20221223131625_preserve_original_format_of_images.js
+++ b/server/db/migrations/20221223131625_preserve_original_format_of_images.js
@@ -93,7 +93,7 @@ module.exports.up = async (knex) => {
   const attachments = await knex('attachment').whereNotNull('image');
 
   // eslint-disable-next-line no-restricted-syntax
-  for (attachment of attachments) {
+  for (const attachment of attachments) {
     // eslint-disable-next-line no-await-in-loop
     const image = await processAttachmentImage(attachment, config.custom.attachmentsPath);
 
diff --git a/server/db/migrations/20221226210239_improve_quality_of_resized_images.js b/server/db/migrations/20221226210239_improve_quality_of_resized_images.js
index fed01d40..b6e1e23c 100644
--- a/server/db/migrations/20221226210239_improve_quality_of_resized_images.js
+++ b/server/db/migrations/20221226210239_improve_quality_of_resized_images.js
@@ -113,7 +113,7 @@ module.exports.up = async (knex) => {
   const users = await knex('user_account').whereNotNull('avatar');
 
   // eslint-disable-next-line no-restricted-syntax
-  for (user of users) {
+  for (const user of users) {
     // eslint-disable-next-line no-await-in-loop
     await processUserAvatar(user, config.custom.userAvatarsPath);
   }
@@ -121,7 +121,7 @@ module.exports.up = async (knex) => {
   const projects = await knex('project').whereNotNull('background_image');
 
   // eslint-disable-next-line no-restricted-syntax
-  for (project of projects) {
+  for (const project of projects) {
     // eslint-disable-next-line no-await-in-loop
     await processProjectBackgroundImage(project, config.custom.projectBackgroundImagesPath);
   }
@@ -129,7 +129,7 @@ module.exports.up = async (knex) => {
   const attachments = await knex('attachment').whereNotNull('image');
 
   // eslint-disable-next-line no-restricted-syntax
-  for (attachment of attachments) {
+  for (const attachment of attachments) {
     // eslint-disable-next-line no-await-in-loop
     await processAttachmentImage(attachment, config.custom.attachmentsPath);
   }
diff --git a/server/db/migrations/20240721171239_languages_with_country_codes.js b/server/db/migrations/20240721171239_languages_with_country_codes.js
new file mode 100644
index 00000000..083dae91
--- /dev/null
+++ b/server/db/migrations/20240721171239_languages_with_country_codes.js
@@ -0,0 +1,68 @@
+const _ = require('lodash');
+
+const LANGUAGES = [
+  'bg-BG',
+  'cs-CZ',
+  'da-DK',
+  'de-DE',
+  'en-US',
+  'es-ES',
+  'fa-IR',
+  'fr-FR',
+  'hu-HU',
+  'id-ID',
+  'it-IT',
+  'ja-JP',
+  'ko-KR',
+  'nl-NL',
+  'pl-PL',
+  'pt-BR',
+  'ro-RO',
+  'ru-RU',
+  'sk-SK',
+  'sv-SE',
+  'tr-TR',
+  'uz-UZ',
+  'zh-CN',
+];
+
+const LANGUAGE_BY_PREV_LANGUAGE = LANGUAGES.reduce(
+  (result, language) => ({
+    ...result,
+    [language.split('-')[0]]: language,
+  }),
+  {},
+);
+LANGUAGE_BY_PREV_LANGUAGE.ua = 'uk-UA';
+
+const PREV_LANGUAGE_BY_LANGUAGE = _.invert(LANGUAGE_BY_PREV_LANGUAGE);
+
+module.exports.up = async (knex) => {
+  const users = await knex('user_account').whereNotNull('language');
+  const prevLanguages = [...new Set(users.map((user) => user.language))];
+
+  // eslint-disable-next-line no-restricted-syntax
+  for (const prevLanguage of prevLanguages) {
+    // eslint-disable-next-line no-await-in-loop
+    await knex('user_account')
+      .update({
+        language: LANGUAGE_BY_PREV_LANGUAGE[prevLanguage],
+      })
+      .where('language', prevLanguage);
+  }
+};
+
+module.exports.down = async (knex) => {
+  const users = await knex('user_account').whereNotNull('language');
+  const languages = [...new Set(users.map((user) => user.language))];
+
+  // eslint-disable-next-line no-restricted-syntax
+  for (const language of languages) {
+    // eslint-disable-next-line no-await-in-loop
+    await knex('user_account')
+      .update({
+        language: PREV_LANGUAGE_BY_LANGUAGE[language],
+      })
+      .where('language', language);
+  }
+};