diff --git a/wp-admin/js/application-passwords.js b/wp-admin/js/application-passwords.js
index 09e4434e2f..b1a20ceb8e 100644
--- a/wp-admin/js/application-passwords.js
+++ b/wp-admin/js/application-passwords.js
@@ -47,7 +47,7 @@
 		request = wp.hooks.applyFilters( 'wp_application_passwords_new_password_request', request, userId );
 
 		wp.apiRequest( {
-			path: '/wp/v2/users/' + userId + '/application-passwords',
+			path: '/wp/v2/users/' + userId + '/application-passwords?_locale=user',
 			method: 'POST',
 			data: request
 		} ).always( function() {
@@ -94,7 +94,7 @@
 		$submitButton.prop( 'disabled', true );
 
 		wp.apiRequest( {
-			path: '/wp/v2/users/' + userId + '/application-passwords/' + uuid,
+			path: '/wp/v2/users/' + userId + '/application-passwords/' + uuid + '?_locale=user',
 			method: 'DELETE'
 		} ).always( function() {
 			$submitButton.prop( 'disabled', false );
@@ -123,7 +123,7 @@
 		$submitButton.prop( 'disabled', true );
 
 		wp.apiRequest( {
-			path: '/wp/v2/users/' + userId + '/application-passwords',
+			path: '/wp/v2/users/' + userId + '/application-passwords?_locale=user',
 			method: 'DELETE'
 		} ).always( function() {
 			$submitButton.prop( 'disabled', false );
diff --git a/wp-admin/js/application-passwords.min.js b/wp-admin/js/application-passwords.min.js
index 0cef7eb19e..95389326ae 100644
--- a/wp-admin/js/application-passwords.min.js
+++ b/wp-admin/js/application-passwords.min.js
@@ -1,2 +1,2 @@
 /*! This file is auto-generated */
-!function(i){var a=i("#application-passwords-section"),o=a.find(".create-application-password"),n=o.find(".input"),t=o.find(".button"),p=a.find(".application-passwords-list-table-wrapper"),r=a.find("tbody"),d=r.find(".no-items"),e=i("#revoke-all-application-passwords"),l=wp.template("new-application-password"),c=wp.template("application-password-row"),w=i("#user_id").val();function u(e,s,a){var o=a;e.responseJSON&&e.responseJSON.message&&(o=e.responseJSON.message),f(o,"error")}function f(e,s){var a=i("<div></div>").attr("role","alert").attr("tabindex","-1").addClass("is-dismissible notice notice-"+s).append(i("<p></p>").text(e)).append(i("<button></button>").attr("type","button").addClass("notice-dismiss").append(i("<span></span>").addClass("screen-reader-text").text(wp.i18n.__("Dismiss this notice."))));return o.after(a),a}function v(){i(".notice",a).remove()}t.click(function(e){if(e.preventDefault(),!t.prop("aria-disabled")){var s=n.val();if(0!==s.length){v(),t.prop("aria-disabled",!0).addClass("disabled");var a={name:s};a=wp.hooks.applyFilters("wp_application_passwords_new_password_request",a,w),wp.apiRequest({path:"/wp/v2/users/"+w+"/application-passwords",method:"POST",data:a}).always(function(){t.removeProp("aria-disabled").removeClass("disabled")}).done(function(e){n.val(""),t.prop("disabled",!1),o.after(l({name:s,password:e.password})),i(".new-application-password-notice").focus(),r.prepend(c(e)),p.show(),d.remove(),wp.hooks.doAction("wp_application_passwords_created_password",e,a)}).fail(u)}else n.focus()}}),r.on("click",".delete",function(e){if(e.preventDefault(),window.confirm(wp.i18n.__("Are you sure you want to revoke this password? This action cannot be undone."))){var s=i(this),a=s.closest("tr"),o=a.data("uuid");v(),s.prop("disabled",!0),wp.apiRequest({path:"/wp/v2/users/"+w+"/application-passwords/"+o,method:"DELETE"}).always(function(){s.prop("disabled",!1)}).done(function(e){e.deleted&&(0===a.siblings().length&&p.hide(),a.remove(),f(wp.i18n.__("Application password revoked."),"success").focus())}).fail(u)}}),e.on("click",function(e){if(e.preventDefault(),window.confirm(wp.i18n.__("Are you sure you want to revoke all passwords? This action cannot be undone."))){var s=i(this);v(),s.prop("disabled",!0),wp.apiRequest({path:"/wp/v2/users/"+w+"/application-passwords",method:"DELETE"}).always(function(){s.prop("disabled",!1)}).done(function(e){e.deleted&&(r.children().remove(),a.children(".new-application-password").remove(),p.hide(),f(wp.i18n.__("All application passwords revoked."),"success").focus())}).fail(u)}}),a.on("click",".notice-dismiss",function(e){e.preventDefault();var s=i(this).parent();s.removeAttr("role"),s.fadeTo(100,0,function(){s.slideUp(100,function(){s.remove(),n.focus()})})}),0===r.children("tr").not(d).length&&p.hide()}(jQuery);
\ No newline at end of file
+!function(i){var a=i("#application-passwords-section"),o=a.find(".create-application-password"),n=o.find(".input"),t=o.find(".button"),p=a.find(".application-passwords-list-table-wrapper"),r=a.find("tbody"),d=r.find(".no-items"),e=i("#revoke-all-application-passwords"),l=wp.template("new-application-password"),c=wp.template("application-password-row"),u=i("#user_id").val();function w(e,s,a){var o=a;e.responseJSON&&e.responseJSON.message&&(o=e.responseJSON.message),f(o,"error")}function f(e,s){var a=i("<div></div>").attr("role","alert").attr("tabindex","-1").addClass("is-dismissible notice notice-"+s).append(i("<p></p>").text(e)).append(i("<button></button>").attr("type","button").addClass("notice-dismiss").append(i("<span></span>").addClass("screen-reader-text").text(wp.i18n.__("Dismiss this notice."))));return o.after(a),a}function v(){i(".notice",a).remove()}t.click(function(e){if(e.preventDefault(),!t.prop("aria-disabled")){var s=n.val();if(0!==s.length){v(),t.prop("aria-disabled",!0).addClass("disabled");var a={name:s};a=wp.hooks.applyFilters("wp_application_passwords_new_password_request",a,u),wp.apiRequest({path:"/wp/v2/users/"+u+"/application-passwords?_locale=user",method:"POST",data:a}).always(function(){t.removeProp("aria-disabled").removeClass("disabled")}).done(function(e){n.val(""),t.prop("disabled",!1),o.after(l({name:s,password:e.password})),i(".new-application-password-notice").focus(),r.prepend(c(e)),p.show(),d.remove(),wp.hooks.doAction("wp_application_passwords_created_password",e,a)}).fail(w)}else n.focus()}}),r.on("click",".delete",function(e){if(e.preventDefault(),window.confirm(wp.i18n.__("Are you sure you want to revoke this password? This action cannot be undone."))){var s=i(this),a=s.closest("tr"),o=a.data("uuid");v(),s.prop("disabled",!0),wp.apiRequest({path:"/wp/v2/users/"+u+"/application-passwords/"+o+"?_locale=user",method:"DELETE"}).always(function(){s.prop("disabled",!1)}).done(function(e){e.deleted&&(0===a.siblings().length&&p.hide(),a.remove(),f(wp.i18n.__("Application password revoked."),"success").focus())}).fail(w)}}),e.on("click",function(e){if(e.preventDefault(),window.confirm(wp.i18n.__("Are you sure you want to revoke all passwords? This action cannot be undone."))){var s=i(this);v(),s.prop("disabled",!0),wp.apiRequest({path:"/wp/v2/users/"+u+"/application-passwords?_locale=user",method:"DELETE"}).always(function(){s.prop("disabled",!1)}).done(function(e){e.deleted&&(r.children().remove(),a.children(".new-application-password").remove(),p.hide(),f(wp.i18n.__("All application passwords revoked."),"success").focus())}).fail(w)}}),a.on("click",".notice-dismiss",function(e){e.preventDefault();var s=i(this).parent();s.removeAttr("role"),s.fadeTo(100,0,function(){s.slideUp(100,function(){s.remove(),n.focus()})})}),0===r.children("tr").not(d).length&&p.hide()}(jQuery);
\ No newline at end of file
diff --git a/wp-admin/js/auth-app.js b/wp-admin/js/auth-app.js
index 4af3a05fa8..ad4403032d 100644
--- a/wp-admin/js/auth-app.js
+++ b/wp-admin/js/auth-app.js
@@ -54,7 +54,7 @@
 		request = wp.hooks.applyFilters( 'wp_application_passwords_approve_app_request', request, context );
 
 		wp.apiRequest( {
-			path: '/wp/v2/users/me/application-passwords',
+			path: '/wp/v2/users/me/application-passwords?_locale=user',
 			method: 'POST',
 			data: request
 		} ).done( function( response, textStatus, jqXHR ) {
diff --git a/wp-admin/js/auth-app.min.js b/wp-admin/js/auth-app.min.js
index cd2fd9dabe..6695f4dc1a 100644
--- a/wp-admin/js/auth-app.min.js
+++ b/wp-admin/js/auth-app.min.js
@@ -1,2 +1,2 @@
 /*! This file is auto-generated */
-!function(r,l){var p=r("#app_name"),i=r("#approve"),e=r("#reject"),d=p.closest("form"),o={userLogin:l.user_login,successUrl:l.success,rejectUrl:l.reject};i.click(function(e){var n=p.val(),a=r('input[name="app_id"]',d).val();if(e.preventDefault(),!i.prop("aria-disabled"))if(0!==n.length){i.prop("aria-disabled",!0).addClass("disabled");var s={name:n};0<a.length&&(s.app_id=a),s=wp.hooks.applyFilters("wp_application_passwords_approve_app_request",s,o),wp.apiRequest({path:"/wp/v2/users/me/application-passwords",method:"POST",data:s}).done(function(e,a,s){wp.hooks.doAction("wp_application_passwords_approve_app_request_success",e,a,s);var p,o,t,i=l.success;i?(p=i+(-1===i.indexOf("?")?"?":"&")+"site_url="+encodeURIComponent(l.site_url)+"&user_login="+encodeURIComponent(l.user_login)+"&password="+encodeURIComponent(e.password),window.location=p):(o=wp.i18n.sprintf('<label for="new-application-password-value">'+wp.i18n.__("Your new password for %s is:")+"</label>","<strong></strong>")+' <input id="new-application-password-value" type="text" class="code" readonly="readonly" value="" />',t=r("<div></div>").attr("role","alert").attr("tabindex",-1).addClass("notice notice-success notice-alt").append(r("<p></p>").addClass("application-password-display").html(o)).append("<p>"+wp.i18n.__("Be sure to save this in a safe location. You will not be able to retrieve it.")+"</p>"),r("strong",t).text(n),r("input",t).val(e.password),d.replaceWith(t),t.focus())}).fail(function(e,a,s){var p=s,o=null;e.responseJSON&&(o=e.responseJSON).message&&(p=o.message);var t=r("<div></div>").attr("role","alert").addClass("notice notice-error").append(r("<p></p>").text(p));r("h1").after(t),i.removeProp("aria-disabled",!1).removeClass("disabled"),wp.hooks.doAction("wp_application_passwords_approve_app_request_success",o,a,e)})}else p.focus()}),e.click(function(e){e.preventDefault(),wp.hooks.doAction("wp_application_passwords_reject_app",o),window.location=l.reject}),d.on("submit",function(e){e.preventDefault()})}(jQuery,authApp);
\ No newline at end of file
+!function(r,l){var o=r("#app_name"),i=r("#approve"),e=r("#reject"),d=o.closest("form"),p={userLogin:l.user_login,successUrl:l.success,rejectUrl:l.reject};i.click(function(e){var n=o.val(),a=r('input[name="app_id"]',d).val();if(e.preventDefault(),!i.prop("aria-disabled"))if(0!==n.length){i.prop("aria-disabled",!0).addClass("disabled");var s={name:n};0<a.length&&(s.app_id=a),s=wp.hooks.applyFilters("wp_application_passwords_approve_app_request",s,p),wp.apiRequest({path:"/wp/v2/users/me/application-passwords?_locale=user",method:"POST",data:s}).done(function(e,a,s){wp.hooks.doAction("wp_application_passwords_approve_app_request_success",e,a,s);var o,p,t,i=l.success;i?(o=i+(-1===i.indexOf("?")?"?":"&")+"site_url="+encodeURIComponent(l.site_url)+"&user_login="+encodeURIComponent(l.user_login)+"&password="+encodeURIComponent(e.password),window.location=o):(p=wp.i18n.sprintf('<label for="new-application-password-value">'+wp.i18n.__("Your new password for %s is:")+"</label>","<strong></strong>")+' <input id="new-application-password-value" type="text" class="code" readonly="readonly" value="" />',t=r("<div></div>").attr("role","alert").attr("tabindex",-1).addClass("notice notice-success notice-alt").append(r("<p></p>").addClass("application-password-display").html(p)).append("<p>"+wp.i18n.__("Be sure to save this in a safe location. You will not be able to retrieve it.")+"</p>"),r("strong",t).text(n),r("input",t).val(e.password),d.replaceWith(t),t.focus())}).fail(function(e,a,s){var o=s,p=null;e.responseJSON&&(p=e.responseJSON).message&&(o=p.message);var t=r("<div></div>").attr("role","alert").addClass("notice notice-error").append(r("<p></p>").text(o));r("h1").after(t),i.removeProp("aria-disabled",!1).removeClass("disabled"),wp.hooks.doAction("wp_application_passwords_approve_app_request_success",p,a,e)})}else o.focus()}),e.click(function(e){e.preventDefault(),wp.hooks.doAction("wp_application_passwords_reject_app",p),window.location=l.reject}),d.on("submit",function(e){e.preventDefault()})}(jQuery,authApp);
\ No newline at end of file
diff --git a/wp-admin/js/site-health.js b/wp-admin/js/site-health.js
index d91b75e90a..9bba750094 100644
--- a/wp-admin/js/site-health.js
+++ b/wp-admin/js/site-health.js
@@ -271,7 +271,7 @@ jQuery( document ).ready( function( $ ) {
 
 				if ( 'undefined' !== typeof( this.has_rest ) && this.has_rest ) {
 					wp.apiRequest( {
-						url: this.test,
+						url: wp.url.addQueryArgs( this.test, { _locale: 'user' } ),
 						headers: this.headers
 					} )
 						.done( function( response ) {
diff --git a/wp-admin/js/site-health.min.js b/wp-admin/js/site-health.min.js
index 18295a79da..cc617fedb5 100644
--- a/wp-admin/js/site-health.min.js
+++ b/wp-admin/js/site-health.min.js
@@ -1,2 +1,2 @@
 /*! This file is auto-generated */
-jQuery(document).ready(function(c){var a,t,s,h=wp.i18n.__,n=wp.i18n._n,o=wp.i18n.sprintf,i=new ClipboardJS(".site-health-copy-buttons .copy-button"),d=c(".health-check-body.health-check-debug-tab").length,r=c("#health-check-accordion-block-wp-paths-sizes");function l(e){var t,s,a=wp.template("health-check-issue"),i=c("#health-check-issues-"+e.status);if(!function(e){var t,s,a,i,n={test:"string",label:"string",description:"string"},o=!0;if("object"!=typeof e)return!1;for(t in n)if("object"==typeof(s=n[t]))for(a in s)i=s[a],void 0!==e[t]&&void 0!==e[t][a]&&i===typeof e[t][a]||(o=!1);else void 0!==e[t]&&s===typeof e[t]||(o=!1);return o}(e))return!1;SiteHealth.site_status.issues[e.status]++,s=SiteHealth.site_status.issues[e.status],void 0===e.test&&(e.test=e.status+s),"critical"===e.status?t=o(n("%s critical issue","%s critical issues",s),'<span class="issue-count">'+s+"</span>"):"recommended"===e.status?t=o(n("%s recommended improvement","%s recommended improvements",s),'<span class="issue-count">'+s+"</span>"):"good"===e.status&&(t=o(n("%s item with no issues detected","%s items with no issues detected",s),'<span class="issue-count">'+s+"</span>")),t&&c(".site-health-issue-count-title",i).html(t),c(".issues","#health-check-issues-"+e.status).append(a(e))}function u(){var e,t,s=c(".site-health-progress"),a=s.closest(".site-health-progress-wrapper"),i=c(".site-health-progress-label",a),n=c(".site-health-progress svg #bar"),o=parseInt(SiteHealth.site_status.issues.good,0)+parseInt(SiteHealth.site_status.issues.recommended,0)+1.5*parseInt(SiteHealth.site_status.issues.critical,0),r=.5*parseInt(SiteHealth.site_status.issues.recommended,0)+1.5*parseInt(SiteHealth.site_status.issues.critical,0),l=100-Math.ceil(r/o*100);0!==o?(a.removeClass("loading"),e=n.attr("r"),l<0&&(l=0),100<l&&(l=100),t=(100-l)/100*(Math.PI*(2*e)),n.css({strokeDashoffset:t}),parseInt(SiteHealth.site_status.issues.critical,0)<1&&c("#health-check-issues-critical").addClass("hidden"),parseInt(SiteHealth.site_status.issues.recommended,0)<1&&c("#health-check-issues-recommended").addClass("hidden"),80<=l&&0===parseInt(SiteHealth.site_status.issues.critical,0)?(a.addClass("green").removeClass("orange"),i.text(h("Good")),wp.a11y.speak(h("All site health tests have finished running. Your site is looking good, and the results are now available on the page."))):(a.addClass("orange").removeClass("green"),i.text(h("Should be improved")),wp.a11y.speak(h("All site health tests have finished running. There are items that should be addressed, and the results are now available on the page."))),d||(c.post(ajaxurl,{action:"health-check-site-status-result",_wpnonce:SiteHealth.nonce.site_status_result,counts:SiteHealth.site_status.issues}),100===l&&(c(".site-status-all-clear").removeClass("hide"),c(".site-status-has-issues").addClass("hide")))):s.addClass("hidden")}function p(e,t){var s;s={status:"recommended",label:h("A test is unavailable"),badge:{color:"red",label:h("Unavailable")},description:"<p>"+e+"</p><p>"+t+"</p>",actions:""},l(wp.hooks.applyFilters("site_status_test_result",s))}i.on("success",function(e){var t=c(e.trigger),s=c(".success",t.closest("div"));e.clearSelection(),t.focus(),clearTimeout(a),s.removeClass("hidden"),a=setTimeout(function(){s.addClass("hidden"),i.clipboardAction.fakeElem&&i.clipboardAction.removeFake&&i.clipboardAction.removeFake()},3e3),wp.a11y.speak(h("Site information has been copied to your clipboard."))}),c(".health-check-accordion").on("click",".health-check-accordion-trigger",function(){"true"===c(this).attr("aria-expanded")?(c(this).attr("aria-expanded","false"),c("#"+c(this).attr("aria-controls")).attr("hidden",!0)):(c(this).attr("aria-expanded","true"),c("#"+c(this).attr("aria-controls")).attr("hidden",!1))}),c(".site-health-view-passed").on("click",function(){var e=c("#health-check-issues-good");e.toggleClass("hidden"),c(this).attr("aria-expanded",!e.hasClass("hidden"))}),"undefined"==typeof SiteHealth||d||(0===SiteHealth.site_status.direct.length&&0===SiteHealth.site_status.async.length?u():SiteHealth.site_status.issues={good:0,recommended:0,critical:0},0<SiteHealth.site_status.direct.length&&c.each(SiteHealth.site_status.direct,function(){l(this)}),0<SiteHealth.site_status.async.length?function t(){var s=!0;1<=SiteHealth.site_status.async.length&&c.each(SiteHealth.site_status.async,function(){var e={action:"health-check-"+this.test.replace("_","-"),_wpnonce:SiteHealth.nonce.site_status};return!!this.completed||(s=!1,this.completed=!0,void 0!==this.has_rest&&this.has_rest?wp.apiRequest({url:this.test,headers:this.headers}).done(function(e){l(wp.hooks.applyFilters("site_status_test_result",e))}).fail(function(e){var t;t=void 0!==e.responseJSON&&void 0!==e.responseJSON.message?e.responseJSON.message:h("No details available"),p(this.url,t)}).always(function(){t()}):c.post(ajaxurl,e).done(function(e){l(wp.hooks.applyFilters("site_status_test_result",e.data))}).fail(function(e){var t;t=void 0!==e.responseJSON&&void 0!==e.responseJSON.message?e.responseJSON.message:h("No details available"),p(this.url,t)}).always(function(){t()}),!1)}),s&&u()}():u()),d&&(r.length?(t=(new Date).getTime(),s=window.setTimeout(function(){wp.a11y.speak(h("Please wait..."))},3e3),wp.apiRequest({path:"/wp-site-health/v1/directory-sizes"}).done(function(e){!function(i){var e=c("button.button.copy-button"),a=e.attr("data-clipboard-text");c.each(i,function(e,t){var s=t.debug||t.size;void 0!==s&&(a=a.replace(e+": loading...",e+": "+s))}),e.attr("data-clipboard-text",a),r.find("td[class]").each(function(e,t){var s=c(t),a=s.attr("class");i.hasOwnProperty(a)&&i[a].size&&s.text(i[a].size)})}(e||{})}).always(function(){var e=(new Date).getTime()-t;c(".health-check-wp-paths-sizes.spinner").css("visibility","hidden"),u(),3e3<e?(e=6e3<e?0:6500-e,window.setTimeout(function(){wp.a11y.speak(h("All site health tests have finished running."))},e)):window.clearTimeout(s),c(document).trigger("site-health-info-dirsizes-done")})):u())});
\ No newline at end of file
+jQuery(document).ready(function(c){var a,t,s,h=wp.i18n.__,n=wp.i18n._n,o=wp.i18n.sprintf,i=new ClipboardJS(".site-health-copy-buttons .copy-button"),d=c(".health-check-body.health-check-debug-tab").length,r=c("#health-check-accordion-block-wp-paths-sizes");function l(e){var t,s,a=wp.template("health-check-issue"),i=c("#health-check-issues-"+e.status);if(!function(e){var t,s,a,i,n={test:"string",label:"string",description:"string"},o=!0;if("object"!=typeof e)return!1;for(t in n)if("object"==typeof(s=n[t]))for(a in s)i=s[a],void 0!==e[t]&&void 0!==e[t][a]&&i===typeof e[t][a]||(o=!1);else void 0!==e[t]&&s===typeof e[t]||(o=!1);return o}(e))return!1;SiteHealth.site_status.issues[e.status]++,s=SiteHealth.site_status.issues[e.status],void 0===e.test&&(e.test=e.status+s),"critical"===e.status?t=o(n("%s critical issue","%s critical issues",s),'<span class="issue-count">'+s+"</span>"):"recommended"===e.status?t=o(n("%s recommended improvement","%s recommended improvements",s),'<span class="issue-count">'+s+"</span>"):"good"===e.status&&(t=o(n("%s item with no issues detected","%s items with no issues detected",s),'<span class="issue-count">'+s+"</span>")),t&&c(".site-health-issue-count-title",i).html(t),c(".issues","#health-check-issues-"+e.status).append(a(e))}function u(){var e,t,s=c(".site-health-progress"),a=s.closest(".site-health-progress-wrapper"),i=c(".site-health-progress-label",a),n=c(".site-health-progress svg #bar"),o=parseInt(SiteHealth.site_status.issues.good,0)+parseInt(SiteHealth.site_status.issues.recommended,0)+1.5*parseInt(SiteHealth.site_status.issues.critical,0),r=.5*parseInt(SiteHealth.site_status.issues.recommended,0)+1.5*parseInt(SiteHealth.site_status.issues.critical,0),l=100-Math.ceil(r/o*100);0!==o?(a.removeClass("loading"),e=n.attr("r"),l<0&&(l=0),100<l&&(l=100),t=(100-l)/100*(Math.PI*(2*e)),n.css({strokeDashoffset:t}),parseInt(SiteHealth.site_status.issues.critical,0)<1&&c("#health-check-issues-critical").addClass("hidden"),parseInt(SiteHealth.site_status.issues.recommended,0)<1&&c("#health-check-issues-recommended").addClass("hidden"),80<=l&&0===parseInt(SiteHealth.site_status.issues.critical,0)?(a.addClass("green").removeClass("orange"),i.text(h("Good")),wp.a11y.speak(h("All site health tests have finished running. Your site is looking good, and the results are now available on the page."))):(a.addClass("orange").removeClass("green"),i.text(h("Should be improved")),wp.a11y.speak(h("All site health tests have finished running. There are items that should be addressed, and the results are now available on the page."))),d||(c.post(ajaxurl,{action:"health-check-site-status-result",_wpnonce:SiteHealth.nonce.site_status_result,counts:SiteHealth.site_status.issues}),100===l&&(c(".site-status-all-clear").removeClass("hide"),c(".site-status-has-issues").addClass("hide")))):s.addClass("hidden")}function p(e,t){var s;s={status:"recommended",label:h("A test is unavailable"),badge:{color:"red",label:h("Unavailable")},description:"<p>"+e+"</p><p>"+t+"</p>",actions:""},l(wp.hooks.applyFilters("site_status_test_result",s))}i.on("success",function(e){var t=c(e.trigger),s=c(".success",t.closest("div"));e.clearSelection(),t.focus(),clearTimeout(a),s.removeClass("hidden"),a=setTimeout(function(){s.addClass("hidden"),i.clipboardAction.fakeElem&&i.clipboardAction.removeFake&&i.clipboardAction.removeFake()},3e3),wp.a11y.speak(h("Site information has been copied to your clipboard."))}),c(".health-check-accordion").on("click",".health-check-accordion-trigger",function(){"true"===c(this).attr("aria-expanded")?(c(this).attr("aria-expanded","false"),c("#"+c(this).attr("aria-controls")).attr("hidden",!0)):(c(this).attr("aria-expanded","true"),c("#"+c(this).attr("aria-controls")).attr("hidden",!1))}),c(".site-health-view-passed").on("click",function(){var e=c("#health-check-issues-good");e.toggleClass("hidden"),c(this).attr("aria-expanded",!e.hasClass("hidden"))}),"undefined"==typeof SiteHealth||d||(0===SiteHealth.site_status.direct.length&&0===SiteHealth.site_status.async.length?u():SiteHealth.site_status.issues={good:0,recommended:0,critical:0},0<SiteHealth.site_status.direct.length&&c.each(SiteHealth.site_status.direct,function(){l(this)}),0<SiteHealth.site_status.async.length?function t(){var s=!0;1<=SiteHealth.site_status.async.length&&c.each(SiteHealth.site_status.async,function(){var e={action:"health-check-"+this.test.replace("_","-"),_wpnonce:SiteHealth.nonce.site_status};return!!this.completed||(s=!1,this.completed=!0,void 0!==this.has_rest&&this.has_rest?wp.apiRequest({url:wp.url.addQueryArgs(this.test,{_locale:"user"}),headers:this.headers}).done(function(e){l(wp.hooks.applyFilters("site_status_test_result",e))}).fail(function(e){var t;t=void 0!==e.responseJSON&&void 0!==e.responseJSON.message?e.responseJSON.message:h("No details available"),p(this.url,t)}).always(function(){t()}):c.post(ajaxurl,e).done(function(e){l(wp.hooks.applyFilters("site_status_test_result",e.data))}).fail(function(e){var t;t=void 0!==e.responseJSON&&void 0!==e.responseJSON.message?e.responseJSON.message:h("No details available"),p(this.url,t)}).always(function(){t()}),!1)}),s&&u()}():u()),d&&(r.length?(t=(new Date).getTime(),s=window.setTimeout(function(){wp.a11y.speak(h("Please wait..."))},3e3),wp.apiRequest({path:"/wp-site-health/v1/directory-sizes"}).done(function(e){!function(i){var e=c("button.button.copy-button"),a=e.attr("data-clipboard-text");c.each(i,function(e,t){var s=t.debug||t.size;void 0!==s&&(a=a.replace(e+": loading...",e+": "+s))}),e.attr("data-clipboard-text",a),r.find("td[class]").each(function(e,t){var s=c(t),a=s.attr("class");i.hasOwnProperty(a)&&i[a].size&&s.text(i[a].size)})}(e||{})}).always(function(){var e=(new Date).getTime()-t;c(".health-check-wp-paths-sizes.spinner").css("visibility","hidden"),u(),3e3<e?(e=6e3<e?0:6500-e,window.setTimeout(function(){wp.a11y.speak(h("All site health tests have finished running."))},e)):window.clearTimeout(s),c(document).trigger("site-health-info-dirsizes-done")})):u())});
\ No newline at end of file
diff --git a/wp-includes/js/api-request.js b/wp-includes/js/api-request.js
index 885e5b47f8..58ef531179 100644
--- a/wp-includes/js/api-request.js
+++ b/wp-includes/js/api-request.js
@@ -10,6 +10,7 @@
  *
  * @since 4.9.0
  * @since 5.6.0 Added overriding of the "PUT" and "DELETE" methods with "POST".
+ *              Added an "application/json" Accept header to all requests.
  * @output wp-includes/js/api-request.js
  */
 
@@ -26,7 +27,7 @@
 		var path = options.path;
 		var method = options.method;
 		var namespaceTrimmed, endpointTrimmed, apiRoot;
-		var headers, addNonceHeader, headerName;
+		var headers, addNonceHeader, addAcceptHeader, headerName;
 
 		if (
 			typeof options.namespace === 'string' &&
@@ -55,19 +56,24 @@
 
 		// If ?_wpnonce=... is present, no need to add a nonce header.
 		addNonceHeader = ! ( options.data && options.data._wpnonce );
+		addAcceptHeader = true;
 
 		headers = options.headers || {};
 
-		// If an 'X-WP-Nonce' header (or any case-insensitive variation
-		// thereof) was specified, no need to add a nonce header.
-		if ( addNonceHeader ) {
-			for ( headerName in headers ) {
-				if ( headers.hasOwnProperty( headerName ) ) {
-					if ( headerName.toLowerCase() === 'x-wp-nonce' ) {
-						addNonceHeader = false;
-						break;
-					}
-				}
+		for ( headerName in headers ) {
+			if ( ! headers.hasOwnProperty( headerName ) ) {
+				continue;
+			}
+
+			// If an 'X-WP-Nonce' or 'Accept' header (or any case-insensitive variation
+			// thereof) was specified, no need to add the header again.
+			switch ( headerName.toLowerCase() ) {
+				case 'x-wp-nonce':
+					addNonceHeader = false;
+					break;
+				case 'accept':
+					addAcceptHeader = false;
+					break;
 			}
 		}
 
@@ -78,6 +84,12 @@
 			}, headers );
 		}
 
+		if ( addAcceptHeader ) {
+			headers = $.extend( {
+				'Accept': 'application/json, */*;q=0.1'
+			}, headers );
+		}
+
 		if ( typeof method === 'string' ) {
 			method = method.toUpperCase();
 
diff --git a/wp-includes/js/api-request.min.js b/wp-includes/js/api-request.min.js
index 63b9c9c2fe..2aedb9567e 100644
--- a/wp-includes/js/api-request.min.js
+++ b/wp-includes/js/api-request.min.js
@@ -1,2 +1,2 @@
 /*! This file is auto-generated */
-!function(w){var c=window.wpApiSettings;function n(e){return e=n.buildAjaxOptions(e),n.transport(e)}n.buildAjaxOptions=function(e){var n,t,o,r,p,a,i=e.url,d=e.path,s=e.method;if("string"==typeof e.namespace&&"string"==typeof e.endpoint&&(n=e.namespace.replace(/^\/|\/$/g,""),d=(t=e.endpoint.replace(/^\//,""))?n+"/"+t:n),"string"==typeof d&&(o=c.root,d=d.replace(/^\//,""),"string"==typeof o&&-1!==o.indexOf("?")&&(d=d.replace("?","&")),i=o+d),p=!(e.data&&e.data._wpnonce),r=e.headers||{},p)for(a in r)if(r.hasOwnProperty(a)&&"x-wp-nonce"===a.toLowerCase()){p=!1;break}return p&&(r=w.extend({"X-WP-Nonce":c.nonce},r)),"string"==typeof s&&("PUT"!==(s=s.toUpperCase())&&"DELETE"!==s||(r=w.extend({"X-HTTP-Method-Override":s},r),s="POST")),delete(e=w.extend({},e,{headers:r,url:i,method:s})).path,delete e.namespace,delete e.endpoint,e},n.transport=w.ajax,window.wp=window.wp||{},window.wp.apiRequest=n}(jQuery);
\ No newline at end of file
+!function(w){var l=window.wpApiSettings;function t(e){return e=t.buildAjaxOptions(e),t.transport(e)}t.buildAjaxOptions=function(e){var t,n,a,p,o,r,i,d=e.url,s=e.path,c=e.method;for(i in"string"==typeof e.namespace&&"string"==typeof e.endpoint&&(t=e.namespace.replace(/^\/|\/$/g,""),s=(n=e.endpoint.replace(/^\//,""))?t+"/"+n:t),"string"==typeof s&&(a=l.root,s=s.replace(/^\//,""),"string"==typeof a&&-1!==a.indexOf("?")&&(s=s.replace("?","&")),d=a+s),o=!(e.data&&e.data._wpnonce),r=!0,p=e.headers||{})if(p.hasOwnProperty(i))switch(i.toLowerCase()){case"x-wp-nonce":o=!1;break;case"accept":r=!1}return o&&(p=w.extend({"X-WP-Nonce":l.nonce},p)),r&&(p=w.extend({Accept:"application/json, */*;q=0.1"},p)),"string"==typeof c&&("PUT"!==(c=c.toUpperCase())&&"DELETE"!==c||(p=w.extend({"X-HTTP-Method-Override":c},p),c="POST")),delete(e=w.extend({},e,{headers:p,url:d,method:c})).path,delete e.namespace,delete e.endpoint,e},t.transport=w.ajax,window.wp=window.wp||{},window.wp.apiRequest=t}(jQuery);
\ No newline at end of file
diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-site-health-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-site-health-controller.php
index 6dbc239ec0..f790dadb04 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-site-health-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-site-health-controller.php
@@ -171,6 +171,7 @@ class WP_REST_Site_Health_Controller extends WP_REST_Controller {
 	 * @return array
 	 */
 	public function test_background_updates() {
+		$this->load_admin_textdomain();
 		return $this->site_health->get_test_background_updates();
 	}
 
@@ -182,6 +183,7 @@ class WP_REST_Site_Health_Controller extends WP_REST_Controller {
 	 * @return array
 	 */
 	public function test_dotorg_communication() {
+		$this->load_admin_textdomain();
 		return $this->site_health->get_test_dotorg_communication();
 	}
 
@@ -193,6 +195,7 @@ class WP_REST_Site_Health_Controller extends WP_REST_Controller {
 	 * @return array
 	 */
 	public function test_loopback_requests() {
+		$this->load_admin_textdomain();
 		return $this->site_health->get_test_loopback_requests();
 	}
 
@@ -204,6 +207,7 @@ class WP_REST_Site_Health_Controller extends WP_REST_Controller {
 	 * @return array
 	 */
 	public function test_authorization_header() {
+		$this->load_admin_textdomain();
 		return $this->site_health->get_test_authorization_header();
 	}
 
@@ -219,6 +223,8 @@ class WP_REST_Site_Health_Controller extends WP_REST_Controller {
 			require_once ABSPATH . 'wp-admin/includes/class-wp-debug-data.php';
 		}
 
+		$this->load_admin_textdomain();
+
 		$sizes_data = WP_Debug_Data::get_sizes();
 		$all_sizes  = array( 'raw' => 0 );
 
@@ -256,6 +262,22 @@ class WP_REST_Site_Health_Controller extends WP_REST_Controller {
 		return $all_sizes;
 	}
 
+	/**
+	 * Loads the admin textdomain for Site Health tests.
+	 *
+	 * The {@see WP_Site_Health} class is defined in WP-Admin, while the REST API operates in a front-end context.
+	 * This means that the translations for Site Health won't be loaded by default in {@see load_default_textdomain()}.
+	 *
+	 * @since 5.6.0
+	 */
+	protected function load_admin_textdomain() {
+		// Accounts for inner REST API requests in the admin.
+		if ( ! is_admin() ) {
+			$locale = determine_locale();
+			load_textdomain( 'default', WP_LANG_DIR . "/admin-$locale.mo" );
+		}
+	}
+
 	/**
 	 * Gets the schema for each site health test.
 	 *
diff --git a/wp-includes/script-loader.php b/wp-includes/script-loader.php
index f3ad2de05c..a0da5a0c4d 100644
--- a/wp-includes/script-loader.php
+++ b/wp-includes/script-loader.php
@@ -1286,7 +1286,7 @@ function wp_default_scripts( $scripts ) {
 		$scripts->add( 'plugin-install', "/wp-admin/js/plugin-install$suffix.js", array( 'jquery', 'jquery-ui-core', 'thickbox' ), false, 1 );
 		$scripts->set_translations( 'plugin-install' );
 
-		$scripts->add( 'site-health', "/wp-admin/js/site-health$suffix.js", array( 'clipboard', 'jquery', 'wp-util', 'wp-a11y', 'wp-api-request' ), false, 1 );
+		$scripts->add( 'site-health', "/wp-admin/js/site-health$suffix.js", array( 'clipboard', 'jquery', 'wp-util', 'wp-a11y', 'wp-api-request', 'wp-url' ), false, 1 );
 		$scripts->set_translations( 'site-health' );
 
 		$scripts->add( 'privacy-tools', "/wp-admin/js/privacy-tools$suffix.js", array( 'jquery', 'wp-a11y' ), false, 1 );
diff --git a/wp-includes/version.php b/wp-includes/version.php
index db316fc067..2cb7334735 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.7-alpha-49713';
+$wp_version = '5.7-alpha-49716';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.