How to Fix Mixed Content Errors After Moving WordPress to HTTPS

Most tutorials claim that switching WordPress to HTTPS is a one-click victory. The reality is that the SSL certificate merely encrypts the connection — it does absolutely nothing to change the mixed content that silently breaks your pages. The fastest fix for a broken padlock icon is not a plugin, but updating the two Site Address (URL) fields in your Settings > General screen, yet nine out of ten site owners skip this step and wonder why their site looks broken.

Mixed content happens when your secure HTTPS page loads resources (images, scripts, stylesheets) over an insecure HTTP connection. Browsers block or warn about these insecure files, which kills trust and tanks SEO. This article gives you a complete, step-by-step playbook to find and fix every mixed-content culprit, from the obvious low-hanging fruit to the deeply buried database serialisation issues.

Before You Start: Back Up Your Site and Database

Every fix below involves changing data in your WordPress database or core files. A single wrong replacement can break your entire site. Use a plugin like UpdraftPlus or your hosting control panel to export a full backup of files and database. Store that backup off-server before you run a single search-and-replace operation.

If your site breaks during the process, restore the backup and reattempt the specific fix with more caution. Patience here saves hours of panic later.

Common Mixed Content Causes After Moving to HTTPS

8 Proven Ways to Fix Mixed Content Errors (Ordered From Easiest to Most Advanced)

1. Update the Site and Home URLs in Settings

Navigate to Settings > General in your WordPress admin dashboard. Verify that both WordPress Address (URL) and Site Address (URL) start with https://. If either still says http://, your site tells browsers — and WordPress internals — to serve everything over HTTP, defeating the purpose of your SSL certificate.

This single setting is the most common cause of mixed content after migration. Correct it immediately and test the front-end.

2. Search and Replace HTTP URLs in the Database

Even after updating Settings > General, many places in the database still hold old HTTP URLs. Use a dedicated plugin like Better Search Replace or Velvet Blues Update URLs to scan the entire database for http://yourdomain.com and replace it with https://yourdomain.com.

Run this tool on all tables: posts, pages, options, postmeta, and comments. Always validate the replacement strings before committing — one typo can break your site entirely. If you need absolute precision, run the replacement via WP-CLI:

wp search-replace 'http://yourdomain.com' 'https://yourdomain.com' --all-tables --verbose

3. Correct Broken URL in Theme and Plugin Files (Hardcoded Paths)

Some themes and plugins hardcode HTTP resources directly into their functions.php or template files. Open your current theme folder via FTP or the WordPress file editor and search for http:// references. Pay special attention to enqueued scripts and stylesheets, favicon paths, and font includes.

If you find any hardcoded HTTP URL, change it to https://. Use a child theme for modifications so updates do not revert your fix.

4. Run a Global Search-and-Replace With Serialisation Awareness

Simple search-and-replace can corrupt serialised data stored in options like widgets or thememods. Use WP Migrate DB or the interconnectit Serialized Search and Replace tool to handle serialisation properly. These tools update string lengths in the database, preventing the white screen of death.

If you skip this step, some widgets or menus may silently fail after your replacement.

5. Check Your .htaccess File for Correct Redirect Rules

An SSL certificate is worthless without a redirect. Open .htaccess in the root of your WordPress install and ensure the following block appears before the # BEGIN WordPress section:

<IfModule modrewrite.c>
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}/$1 [R=301,L]
</IfModule>

This forces every visitor to the HTTPS version. If your server already sets HTTPS at the Nginx or load-balancer level, skip the .htaccess redirect and instead adjust the WordPress site URL directly.

6. Fix Mixed Content From CDN or External Sources

Third-party resources (Google Fonts, YouTube embeds, analytics scripts, ad networks) often remain on HTTP. Open your browser console (F12 > Console) and look for warnings that say Mixed Content. The console lists the exact URL of the offending resource. Contact the third-party service to get an HTTPS endpoint, or use a plugin like SSL Insecure Content Fixer to automatically rewrite those URLs.

SSL Insecure Content Fixer offers four levels of detection — start with Simple, escalate to Content or Widgets if needed. It handles many external sources automatically.

7. Override Default URL Generation With a Filter

If dynamic content (e.g., RSS feeds, REST API responses) still returns HTTP references, add this filter to your theme's functions.php file:

addfilter('scriptloadersrc', 'agnostichttps_fixer', 10, 2);
addfilter('styleloadersrc', 'agnostichttps_fixer', 10, 2);
function agnostichttpsfixer($src, $handle) {
    return str_replace('http:', 'https:', $src);
}

This forces all enqueued scripts and stylesheets to use HTTPS regardless of how the theme or plugin registered them. Test thoroughly after adding this code.

8. Review CDN and Reverse Proxy Settings (Cloudflare, Rackspace, etc.)

When using a reverse proxy like Cloudflare, you must configure WordPress to recognise HTTPS at the proxy level. Add this to your wp-config.php file:

if (isset($SERVER['HTTPXFORWARDEDPROTO']) && $SERVER['HTTPXFORWARDEDPROTO'] == 'https') {
    $_SERVER['HTTPS'] = 'on';
}

Without this snippet, WordPress thinks all traffic is HTTP and continues generating mixed content URLs. Also enable Full (Strict) SSL in your Cloudflare dashboard to ensure the connection between Cloudflare and your server is encrypted.

How to Prevent Mixed Content Moving Forward

Make HTTPS the default mindset. When installing plugins or themes, check their documentation for HTTPS compatibility. Use relative paths (e.g., //yourdomain.com/image.jpg) or protocol-relative URLs wherever your code allows, though modern practice favours explicit https://.

Set up a regular monitoring schedule. Free tools like SSL Checker or Why No Padlock scan your site for mixed content and email you when a new insecure resource appears. Catch problems before your visitors do.

If you manage multiple client sites, consider an automated workflow that validates HTTPS health after each deployment. Platforms like nativeWP can schedule and publish SEO content once your site is secure, but the security audit should always come first.

Frequently Asked Questions

What is mixed content in WordPress?

Mixed content occurs when a secure HTTPS page includes resources (images, scripts, stylesheets) loaded over the older HTTP protocol. Browsers block or warn about these insecure elements, breaking page functionality and damaging security trust.

Will a plugin automatically fix all mixed content errors?

Plugins like SSL Insecure Content Fixer or Really Simple SSL fix most surface-level mixed content by rewriting HTTP URLs on the fly. However, deeply embedded hardcoded URLs in theme files or serialised database entries often require manual intervention. Use plugins as a first step, then audit with browser developer tools.

Why do I still see mixed content after using a search-and-replace plugin?

Simple search-and-replace tools may miss serialised data used by WordPress options and widgets. When a replacement changes the length of a string without updating the serialisation headers, those entries become corrupt. Use a serialisation-safe replacement tool like WP Migrate DB to avoid this issue.

Do I need to fix mixed content if I only use a staging test site?

Yes. If your staging site is publicly accessible or used to demonstrate work to clients, mixed content warnings give a poor impression. More importantly, when you migrate the staging site to production, the old HTTP references carry over, multiplying cleanup work. Treat staging and production with equal HTTPS rigour.

How do I find all mixed content resources on a specific page?

Open your browser developer tools (F12), navigate to the Console tab, and look for messages containing Mixed Content. Click the specific message to reveal the full URL of the insecure resource. Use this list to target your database search or to contact the third-party provider for an HTTPS endpoint.

Key Takeaways