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Mixed Content Errors Explained | How to Fix HTTPS Security Warnings
Learn what mixed content errors are, why they occur after enabling HTTPS, how they affect website security, and how to fix them to ensure a fully secure website.
A mixed content error occurs when a secure HTTPS webpage attempts to load resources over an insecure HTTP connection.
Although the webpage itself is encrypted using HTTPS, some elements such as images, JavaScript files, stylesheets, fonts, or videos are still being loaded using HTTP. Modern browsers recognise this as a security risk and either display warnings or block the insecure resources entirely.
Mixed content is one of the most common issues website owners encounter after installing an SSL certificate.
When a website contains mixed content, visitors no longer receive the full security benefits of HTTPS.
Browsers such as Google Chrome, Microsoft Edge, Firefox, and Safari may display security warnings or block insecure resources completely.
Common consequences include:
Broken website functionality
Missing images or styling
Browser security warnings
Reduced visitor trust
Lower overall website security
Failed security scans
A secure website should ensure that every resource is loaded over HTTPS.
Mixed content falls into two categories.
Active mixed content includes resources that can directly modify the behaviour of a webpage.
Examples include:
JavaScript files
CSS stylesheets
AJAX requests
Embedded iframes
Because these resources could be manipulated by attackers, modern browsers usually block them automatically.
Passive mixed content includes resources that do not directly change website functionality.
Examples include:
Images
Videos
Audio files
While less dangerous than active content, browsers may still display security warnings because these resources are delivered over an insecure connection.
Mixed content usually appears after migrating a website from HTTP to HTTPS.
Typical causes include:
Hardcoded HTTP image links
Old CSS or JavaScript references
Plugins generating HTTP URLs
Third-party resources loaded over HTTP
Incorrect CMS settings
Legacy website content
Many older websites continue referencing HTTP resources even after SSL has been installed.
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Modern browsers actively protect users against mixed content.
Depending on the type of resource, browsers may:
Automatically upgrade HTTP requests to HTTPS when possible
Block insecure scripts and stylesheets
Display "Not Secure" warnings
Prevent certain resources from loading
This behaviour helps protect visitors from malicious content and man-in-the-middle attacks.
Several tools can identify mixed content issues quickly.
Useful methods include:
Browser Developer Tools
Website Security Scanner
SSL Checker
HostedScan Website Security Scanner
SecurityHeaders.com
Mozilla Observatory
These tools help locate insecure resources that require updating.
Resolving mixed content is usually straightforward.
Recommended steps include:
Replace all HTTP URLs with HTTPS.
Update internal image and media links.
Correct CSS and JavaScript references.
Review third-party integrations.
Update WordPress Site URL settings.
Clear website caches after making changes.
Perform another security scan to confirm the issue has been resolved.
After all resources load securely over HTTPS, browsers will display the secure padlock again.
WordPress websites commonly experience mixed content after installing an SSL certificate.
Typical causes include:
Old media library URLs
Theme files
Plugins
Cached content
Database entries containing HTTP links
Many SSL plugins can help identify and automatically replace insecure URLs, but manually reviewing important pages is still recommended.
To avoid future mixed content problems:
Always use HTTPS links.
Avoid hardcoded HTTP URLs.
Regularly scan your website.
Keep plugins and themes updated.
Monitor browser console warnings.
Test new pages after publishing.
Maintaining a fully encrypted website improves both security and user confidence.
A mixed content error occurs when an HTTPS webpage loads one or more resources over an insecure HTTP connection.
Mixed content is not a direct ranking factor, but browser warnings and poor user experience can negatively impact visitor trust and website quality.
Most modern browsers automatically block active mixed content and may warn users about passive mixed content.
No. Installing an SSL certificate secures your website connection, but all internal resources must also be updated to use HTTPS.
You can use browser Developer Tools, online website security scanners, or professional SSL testing tools to detect mixed content errors.
Mixed content errors are one of the most common issues encountered after migrating a website to HTTPS.
Although the website itself may have a valid SSL certificate, loading insecure resources weakens browser security and reduces visitor confidence.
By ensuring every image, script, stylesheet, and external resource is served securely over HTTPS, website owners can maintain a fully encrypted browsing experience and provide stronger protection for their visitors.
