diff --git a/src/core/classes/site.ts b/src/core/classes/site.ts
index b22ad2110..5cd67966d 100644
--- a/src/core/classes/site.ts
+++ b/src/core/classes/site.ts
@@ -40,6 +40,7 @@ import { CoreWSError } from '@classes/errors/wserror';
 import { CoreLogger } from '@singletons/logger';
 import { Translate } from '@singletons';
 import { CoreIonLoadingElement } from './ion-loading';
+import { CoreLang } from '@services/lang';
 
 /**
  * QR Code type enumeration.
@@ -574,9 +575,14 @@ export class CoreSite {
 
             // Call the WS.
             try {
+                // Send the language to use. Do it after checking cache to prevent losing offline data when changing language.
+                data.moodlewssettinglang = preSets.lang ?? await CoreLang.getCurrentLanguage();
+                data.moodlewssettinglang = data.moodlewssettinglang.replace('-', '_'); // Moodle uses underscore instead of dash.
+
                 const response = await this.callOrEnqueueRequest<T>(method, data, preSets, wsPreSets);
 
                 if (preSets.saveToCache) {
+                    delete data.moodlewssettinglang;
                     this.saveToCache(method, data, response, preSets);
                 }
 
@@ -786,7 +792,8 @@ export class CoreSite {
             return;
         }
 
-        const requestsData = {
+        let lang: string | undefined;
+        const requestsData: Record<string, unknown> = {
             requests: requests.map((request) => {
                 const args = {};
                 const settings = {};
@@ -799,6 +806,11 @@ export class CoreSite {
                         if (match[1] == 'settingfilter' || match[1] == 'settingfileurl') {
                             // Undo special treatment of these settings in CoreWSProvider.convertValuesToString.
                             value = (value == 'true' ? '1' : '0');
+                        } else if (match[1] == 'settinglang') {
+                            // Use the lang globally to avoid exceptions with languages not installed.
+                            lang = value;
+
+                            return;
                         }
                         settings[match[1]] = value;
                     } else {
@@ -813,6 +825,7 @@ export class CoreSite {
                 };
             }),
         };
+        requestsData.moodlewssettinglang = lang;
 
         const wsPresets: CoreWSPreSets = {
             siteUrl: this.siteUrl,
@@ -1942,6 +1955,11 @@ export type CoreSiteWSPreSets = {
      */
     rewriteurls?: boolean;
 
+    /**
+     * Language to send to the WebService (moodlewssettinglang). Defaults to app's language.
+     */
+    lang?: string;
+
     /**
      * Defaults to true. Set to false when the expected response is null.
      */
diff --git a/src/core/features/settings/pages/general/general.ts b/src/core/features/settings/pages/general/general.ts
index 344164a37..e8ef89874 100644
--- a/src/core/features/settings/pages/general/general.ts
+++ b/src/core/features/settings/pages/general/general.ts
@@ -23,6 +23,8 @@ import { CoreSettingsHelper, CoreColorScheme, CoreZoomLevel } from '../../servic
 import { CoreApp } from '@services/app';
 import { CoreIframeUtils } from '@services/utils/iframe';
 import { Diagnostic } from '@singletons';
+import { CoreSites } from '@services/sites';
+import { CoreUtils } from '@services/utils/utils';
 
 /**
  * Page that displays the general settings.
@@ -109,7 +111,11 @@ export class CoreSettingsGeneralPage {
      * Called when a new language is selected.
      */
     languageChanged(): void {
-        CoreLang.changeCurrentLanguage(this.selectedLanguage).finally(() => {
+        CoreLang.changeCurrentLanguage(this.selectedLanguage).finally(async () => {
+            // Invalidate cache for all sites to get the content in the right language.
+            const sites = await CoreSites.getSitesInstances();
+            await CoreUtils.ignoreErrors(Promise.all(sites.map((site) => site.invalidateWsCache())));
+
             CoreEvents.trigger(CoreEvents.LANGUAGE_CHANGED, this.selectedLanguage);
         });
     }
diff --git a/src/core/services/sites.ts b/src/core/services/sites.ts
index fd3d4c85b..702ca7a50 100644
--- a/src/core/services/sites.ts
+++ b/src/core/services/sites.ts
@@ -1145,6 +1145,17 @@ export class CoreSitesProvider {
         return sites.map((site) => site.id);
     }
 
+    /**
+     * Get instances of all stored sites.
+     *
+     * @return Promise resolved when the sites are retrieved.
+     */
+    async getSitesInstances(): Promise<CoreSite[]> {
+        const siteIds = await this.getSitesIds();
+
+        return await Promise.all(siteIds.map(async (siteId) => await this.getSite(siteId)));
+    }
+
     /**
      * Login the user in a site.
      *