{"id":1967049,"date":"2025-10-06T06:27:00","date_gmt":"2025-10-06T10:27:00","guid":{"rendered":"https:\/\/theeventscalendar.com\/knowledgebase\/?p=1967049"},"modified":"2026-04-14T13:55:32","modified_gmt":"2026-04-14T17:55:32","slug":"cors-and-mixed-content-errors","status":"publish","type":"post","link":"https:\/\/theeventscalendar.com\/knowledgebase\/cors-and-mixed-content-errors\/","title":{"rendered":"Troubleshooting CORS and Mixed Content Errors with The Events Calendar"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\" id=\"h-mixed-content-or-https-issues\">Mixed Content or HTTPS Issues<\/h2>\n\n\n\n<p>If your website is showing a <strong>\u201cNot Secure\u201d<\/strong> warning or your events page isn&#8217;t loading styles or scripts correctly after switching to HTTPS, you&#8217;re likely facing a <strong>mixed content<\/strong> issue. This happens when your site loads some resources (like images, scripts, or stylesheets) over HTTP on a page served over HTTPS..<\/p>\n\n\n\n<p>When a secure (HTTPS) page loads a resource (such as an image, iframe, script, or stylesheet) using an insecure (HTTP) URL, browsers may block those resources or show warnings, breaking functionality or layout.<\/p>\n\n\n\n<p>Open <strong>Developer Tools<\/strong> in Chrome (F12 or right-click \u2192 Inspect), go to the <strong>Console tab<\/strong>, and refresh the page. Look for errors mentioning <code>Mixed Content<\/code>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"h-common-symptoms\">Common Symptoms<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Event pages are missing styles or scripts<\/li>\n\n\n\n<li>Console errors like:<\/li>\n\n\n\n<li><code>Mixed Content: The page was loaded over HTTPS, but requested an insecure resource http:\/\/example.com\/...<\/code><\/li>\n\n\n\n<li>Browser warnings: <strong>\u201cNot Secure\u201d<\/strong> in the address bar<\/li>\n\n\n\n<li>Embedded maps or videos fail to load<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">How to Fix Mixed Content Issues<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Update Site URLs<\/strong><br>Ensure your WordPress and Site URLs use <code>https:\/\/<\/code>.<br>Go to:<br><strong>WordPress Dashboard \u2192 Settings \u2192 General<\/strong><br>Update both fields to begin with <code>https:\/\/<\/code>.<br><\/li>\n\n\n\n<li><strong>Use a Mixed Content Fixer Plugin<\/strong><br>Install a plugin like <a href=\"https:\/\/wordpress.org\/plugins\/really-simple-ssl\/\" target=\"_blank\" rel=\"noreferrer noopener\">Really Simple SSL<\/a>. It detects mixed content and helps you transition to HTTPS safely.<br><\/li>\n\n\n\n<li><strong>Replace Old HTTP Links in the Database<\/strong><br>Use a plugin like <a href=\"https:\/\/wordpress.org\/plugins\/better-search-replace\/\" target=\"_blank\" rel=\"noreferrer noopener\">Better Search Replace<\/a> to scan and update old <code>http:\/\/<\/code> URLs in your posts, pages, and settings:<br>\ud83d\udd0dSearch for: <code>http:\/\/yourdomain.com<\/code><br>\ud83d\udc49Replace with: <code>https:\/\/yourdomain.com<\/code><br><br>Run a <strong>dry run first<\/strong> to preview changes.<br><\/li>\n\n\n\n<li><strong>Update Theme or Plugin Assets<\/strong>ot drag-and-drop Elementor building.<br>If your theme or plugins (including custom code) load scripts or styles using hardcoded HTTP URLs, update those to use <code>https:\/\/<\/code> or protocol-relative URLs (<code>\/\/<\/code>).<br><\/li>\n\n\n\n<li><strong>Check Embedded Content<\/strong><br>Ensure embedded resources (like maps, iframes, or videos) use HTTPS. For example, if you&#8217;re embedding a Google Map, use the HTTPS version of the embed code.<br><\/li>\n<\/ol>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-cors-errors-no-access-control-allow-origin\">CORS Errors: \u2018No Access-Control-Allow-Origin\u2019<\/h2>\n\n\n\n<p>When your browser console shows something like:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: jscript; title: ; notranslate\" title=\"\">\nAccess to XMLHttpRequest at &#039;https:\/\/api.example.com\/data&#039; from origin &#039;https:\/\/yourwpdomain.com&#039; has been blocked by CORS policy: No &#039;Access-Control-Allow-Origin&#039; header is present on the requested resource.  \nFailed to load resource: net::ERR_FAILED\n<\/pre><\/div>\n\n\n<p>\u2026that means your WordPress frontend (or a plugin\/theme script) tried to make an AJAX \/ fetch \/ XHR request to another domain (or a different origin: domain, port, or protocol) but the <strong>server that receives the request did not include a response header<\/strong> telling the browser it\u2019s okay to share the resource with your WP site\u2019s origin. Browsers block access when that header is missing (for security).<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"h-how-to-diagnose-the-error\">How to Diagnose the Error<\/h3>\n\n\n\n<p><strong>1. Check the Browser Console &amp; Network Tab<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Look for the failed request(s) and inspect the <strong>Response Headers<\/strong>.<\/li>\n\n\n\n<li>If you don\u2019t see <code>Access-Control-Allow-Origin<\/code>, that confirms the CORS header is missing.<\/li>\n\n\n\n<li>Also check the <strong>Request headers \/ preflight (OPTIONS)<\/strong>, especially for \u201ccomplex\u201d requests (custom headers, non-GET\/POST).<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-video\"><video controls src=\"https:\/\/images.theeventscalendar.com\/kb\/uploads\/2025\/10\/Screen-Recording-2025-10-06-at-01.53.23.86-PM.mp4\"><\/video><\/figure>\n\n\n\n<p><\/p>\n\n\n\n<p><strong>2. Identify Which Code \/ Plugin \/ Theme Is Making the Cross-Origin Request<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Maybe a plugin is reaching out to an API on another domain.<\/li>\n\n\n\n<li>Maybe your theme is loading assets or fonts from another domain.<\/li>\n\n\n\n<li>If using a headless architecture, your frontend and WP backend may be on separate domains.<\/li>\n<\/ul>\n\n\n\n<p><strong>3. Check if the Target Server \/ Resource Allows CORS<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>If the resource is on external servers you don\u2019t control, you may not be able to add headers there.<\/li>\n\n\n\n<li>Use tools (curl, Postman) to fetch the same resource and see whether the <code>Access-Control-Allow-Origin<\/code> header is present in responses.<\/li>\n<\/ul>\n\n\n\n<p><strong>4. Look at Caching &amp; Proxy Layers<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Sometimes caching plugins (or server\/CDN) strip or don&#8217;t pass headers properly.<\/li>\n\n\n\n<li>If you use a reverse proxy (NGINX, Varnish) or CDN (Cloudflare, etc.), headers may be lost or overridden.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"h-how-to-fix-it\">How to Fix It<\/h3>\n\n\n\n<p>Below are approaches you can use <em>within<\/em> WordPress (or its server environment) to add or enable the correct CORS headers.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"h-option-a-add-cors-headers-via-a-plugin\">Option A: Add CORS Headers via a plugin<\/h4>\n\n\n\n<p>There are some WP plugins designed to handle CORS headers:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong><a href=\"https:\/\/wordpress.org\/plugins\/enable-cors\/\">Enable CORS<\/a><\/strong> \u2014 a plugin that lets you specify which origins are allowed.<\/li>\n<\/ul>\n\n\n\n<p>Activate the plugin, configure allowed origin(s), and then test your cross-origin requests.<\/p>\n\n\n\n<p><strong>Note:<\/strong> Some users still report CORS errors even after using a plugin. In those cases, the plugin may conflict with headers added elsewhere or be overridden by server \/ caching layers.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"h-option-b-server-htaccess-web-server-configuration\">Option B: Server \/ .htaccess \/ Web Server Configuration<\/h4>\n\n\n\n<p>If you have control over your server (Apache, NGINX, etc.), the more robust way is to configure headers at the server level (so that all responses include the CORS directives). Examples:<\/p>\n\n\n\n<p>In your WordPress root <code>.htaccess<\/code>, add:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: xml; title: ; notranslate\" title=\"\">\n&lt;IfModule mod_headers.c&gt;\n  Header set Access-Control-Allow-Origin &quot;*&quot;\n  Header set Access-Control-Allow-Methods &quot;GET, POST, OPTIONS, PUT, DELETE&quot;\n  Header set Access-Control-Allow-Headers &quot;Origin, X-Requested-With, Content-Type, Accept, Authorization&quot;\n&lt;\/IfModule&gt;\n<\/pre><\/div>\n\n\n<div style=\"height:30px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p class=\"has-theme-palette-8-background-color has-background\">Important Note: Create a backup of the htaccess file before making any changes.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\" id=\"h-option-c-use-a-proxy-relay\">Option C: Use a Proxy \/ Relay<\/h4>\n\n\n\n<p>If the resource you are fetching is on a third-party server and you can\u2019t control its headers, you can enact a <strong>server-side proxy<\/strong> in WordPress. Workflow:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Frontend calls your WP site (same origin).<\/li>\n\n\n\n<li>WP code (custom endpoint or plugin) forwards the request to the external server.<\/li>\n\n\n\n<li>WP gets the response and returns it to the frontend <strong>with your own CORS headers<\/strong>.<\/li>\n<\/ol>\n\n\n\n<p>This circumvents the browser\u2019s CORS restrictions because the browser only sees your domain.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Mixed Content or HTTPS Issues If your website is showing a \u201cNot Secure\u201d warning or your events page isn&#8217;t loading styles or scripts correctly after switching to HTTPS, you&#8217;re likely facing a mixed content issue. This happens when your site loads some resources (like images, scripts, or stylesheets) over HTTP on a page served over&#8230;<\/p>\n","protected":false},"author":27,"featured_media":1955565,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_kad_blocks_custom_css":"","_kad_blocks_head_custom_js":"","_kad_blocks_body_custom_js":"","_kad_blocks_footer_custom_js":"","_swpsp_post_exclude":false,"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"ep_exclude_from_search":false,"footnotes":""},"categories":[93,108],"tags":[259,109],"stellar-product-taxonomy":[161],"class_list":["post-1967049","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-errors","category-wordpress","tag-troubleshooting","tag-wordpress","stellar-product-taxonomy-the-events-calendar"],"acf":[],"taxonomy_info":{"category":[{"value":93,"label":"Troubleshooting"},{"value":108,"label":"WordPress"}],"post_tag":[{"value":259,"label":"Troubleshooting"},{"value":109,"label":"WordPress"}],"stellar-product-taxonomy":[{"value":161,"label":"The Events Calendar"}]},"featured_image_src_large":["https:\/\/images.theeventscalendar.com\/kb\/uploads\/2023\/02\/social-share-1024x538.png",1024,538,true],"author_info":{"display_name":"Abz","author_link":"https:\/\/theeventscalendar.com\/knowledgebase\/author\/abz\/"},"comment_info":0,"category_info":[{"term_id":93,"name":"Troubleshooting","slug":"errors","term_group":0,"term_taxonomy_id":93,"taxonomy":"category","description":"","parent":0,"count":76,"filter":"raw","term_order":"0","cat_ID":93,"category_count":76,"category_description":"","cat_name":"Troubleshooting","category_nicename":"errors","category_parent":0},{"term_id":108,"name":"WordPress","slug":"wordpress","term_group":0,"term_taxonomy_id":108,"taxonomy":"category","description":"","parent":0,"count":15,"filter":"raw","term_order":"0","cat_ID":108,"category_count":15,"category_description":"","cat_name":"WordPress","category_nicename":"wordpress","category_parent":0}],"tag_info":[{"term_id":259,"name":"Troubleshooting","slug":"troubleshooting","term_group":0,"term_taxonomy_id":259,"taxonomy":"post_tag","description":"","parent":0,"count":14,"filter":"raw","term_order":"0"},{"term_id":109,"name":"WordPress","slug":"wordpress","term_group":0,"term_taxonomy_id":109,"taxonomy":"post_tag","description":"","parent":0,"count":5,"filter":"raw","term_order":"0"}],"_links":{"self":[{"href":"https:\/\/theeventscalendar.com\/knowledgebase\/wp-json\/wp\/v2\/posts\/1967049","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/theeventscalendar.com\/knowledgebase\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/theeventscalendar.com\/knowledgebase\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/theeventscalendar.com\/knowledgebase\/wp-json\/wp\/v2\/users\/27"}],"replies":[{"embeddable":true,"href":"https:\/\/theeventscalendar.com\/knowledgebase\/wp-json\/wp\/v2\/comments?post=1967049"}],"version-history":[{"count":6,"href":"https:\/\/theeventscalendar.com\/knowledgebase\/wp-json\/wp\/v2\/posts\/1967049\/revisions"}],"predecessor-version":[{"id":1969041,"href":"https:\/\/theeventscalendar.com\/knowledgebase\/wp-json\/wp\/v2\/posts\/1967049\/revisions\/1969041"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/theeventscalendar.com\/knowledgebase\/wp-json\/wp\/v2\/media\/1955565"}],"wp:attachment":[{"href":"https:\/\/theeventscalendar.com\/knowledgebase\/wp-json\/wp\/v2\/media?parent=1967049"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/theeventscalendar.com\/knowledgebase\/wp-json\/wp\/v2\/categories?post=1967049"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/theeventscalendar.com\/knowledgebase\/wp-json\/wp\/v2\/tags?post=1967049"},{"taxonomy":"stellar-product-taxonomy","embeddable":true,"href":"https:\/\/theeventscalendar.com\/knowledgebase\/wp-json\/wp\/v2\/stellar-product-taxonomy?post=1967049"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}