Fix Mixed Content Errors on Your HTTPS Site
Mixed content errors appear when an HTTPS page loads one or more resources — scripts, stylesheets, images, or fonts — over plain HTTP. Browsers block or warn on these requests, which can break page functionality, suppress the padlock, and erode visitor trust. This guide shows you how to find every insecure reference, fix it at the source, and verify the clean result.
What This Means
There are two categories of mixed content and they carry very different risk levels. Active mixed content — scripts, iframes, and stylesheets — is blocked outright by modern browsers because it can directly execute in the page context and undermine the HTTPS trust model. Passive mixed content — images, audio, and video — is loaded with a warning rather than blocked, but it still degrades the secure indicator and can expose visitor data on unencrypted channels. The right fix order is active content first, then passive. In both cases the root cause is usually a stale hardcoded URL left behind after an HTTPS migration, a CMS content field that still stores an HTTP absolute URL, or a third-party widget that has not been updated by its vendor. Fixing the symptom on the rendered page without correcting the source template or content field means the problem returns on the next publish or deploy.
| Asset type | What to verify | Why it matters |
|---|---|---|
| Scripts | Any HTTP script or injected third-party asset | Active mixed content can directly weaken execution trust. |
| Stylesheets | Hardcoded HTTP CSS or font loads | These still degrade browser security and consistency. |
| Images and media | Passive HTTP assets after migration | Lower risk than scripts, but still noisy and trust-reducing. |
| Generated content | CMS, theme, or build-time asset URLs | These often keep reintroducing the same problem. |
Common Causes
Patterns worth checking first
- Incomplete migration: Templates or CMS content still reference old HTTP asset URLs.
- Third-party dependencies: A vendor script or widget still loads insecure subresources.
- Rewrite gaps: CDN or proxy rules did not normalize every asset path consistently.
How To Confirm It Safely
Confirmation steps
- Identify whether the issue affects scripts, styles, images, or generated content.
- Check whether the insecure URL is hardcoded, CMS-managed, or third-party controlled.
- Confirm whether the asset is still needed before rewriting it.
- Capture the public page path where the issue is observed for rerun validation.
Fix Workflow
- Remove active mixed content first. Prioritize scripts and other high-risk assets before passive content cleanup.
- Replace stale URLs at the source. Fix templates, CMS content, or build logic so the issue does not reappear.
- Update or remove third-party dependencies. Require HTTPS-only asset loading from external providers.
- Retest the public page. Confirm the insecure references are gone from the live HTTPS response.
Implementation Examples
https://cdn.example.com/app.jsRollout Risks
Quick search-and-replace can miss CMS or generated asset sources
The visible page is often assembled from multiple content sources.
- Fix the generator, not only the output.
- Retest the rendered public page after each change.
Third-party assets can regress after vendor updates
A provider may still serve or reference insecure resources later.
- Review vendor documentation.
- Monitor high-risk pages after the initial cleanup.
Validation Checklist
Post-fix validation
- Active mixed-content issues are removed from public HTTPS pages.
- Passive insecure assets are reduced or eliminated where practical.
- The source of the insecure reference was fixed, not only the symptom.
- The Mixed Content Checker confirms the cleaner asset profile.
Frequently Asked Questions
Mixed content is any HTTP resource loaded on an HTTPS page. Browsers block or warn because allowing unencrypted resources on a secure page weakens the transport guarantee. Active mixed content (scripts, iframes) is blocked silently by default in Chrome and Firefox. Passive mixed content (images, video) triggers a warning but still loads in most browsers. Even passive mixed content removes the padlock and can expose user data on the unencrypted channel.