SSL Mixed Content Errors Explained: Why Your Padlock Disappears After a Redesign

A business relaunches its website, new theme, new developer, sometimes a new platform entirely, and within days someone notices the padlock icon has a warning triangle on it, or the URL bar drops the secure indicator altogether. The confusing part: the SSL certificate itself hasn't changed or expired. What broke is something a redesign disturbs constantly and almost nobody checks for before going live: mixed content.

What Mixed Content Actually Means

Mixed content happens when a page loaded over secure HTTPS still pulls in some resource, an image, a script, a stylesheet, a font, over plain unencrypted HTTP. Browsers flag this because that one unencrypted resource is a potential point where an attacker could intercept or alter what loads on an otherwise secure page, so they warn the user even though the page's own certificate is completely valid.

Why Redesigns Specifically Cause This

A certificate that's been working fine for months doesn't suddenly break on its own. A redesign changes it because of exactly the kind of details that get lost in a big migration: a new theme importing a font or icon library from a CDN link that was copy-pasted with an old http:// prefix still attached; a developer hardcoding a handful of image URLs by absolute path during content migration instead of using relative paths; a new third-party embed, a chat widget, a review plugin, a booking calendar, loading its own script over HTTP by default; or old content in the database (blog posts, product descriptions) containing image tags written years ago with http:// links that nobody thought to touch during the redesign.

How to Actually Find Every Instance

Open your browser's developer tools (F12), go to the Console tab, and reload the page. Mixed content warnings list the exact URL of every offending resource directly, no guessing required. For WordPress sites, a plugin like "Better Search Replace" or a bulk find-and-replace directly on the database can catch hardcoded http:// links across old posts and pages in one pass, far faster than checking page by page. For custom-built sites, search the codebase directly for "http://" references pointing to your own domain or commonly embedded third-party assets.

The Places Mixed Content Hides Most Often

• Old blog or product content with image tags written before the site had SSL at all, now surfaced fresh by a redesign that reused the same content.
• Third-party widgets and embeds, chat tools, review plugins, maps, added during the redesign without checking whether their default embed code uses HTTPS.
• CDN and font links copy-pasted from an old code snippet or tutorial that still specifies http:// explicitly.
• Background images set via inline CSS or theme customizer settings, easy to miss because they don't show up in a simple "view source" scan of the HTML.

The Fix, Once You've Found Everything

Change every identified http:// reference to https://, or better, to a protocol-relative or fully relative path where possible so this specific problem can't recur on a future domain or platform change. Re-check the developer console after each fix, since some resources only trigger their own downstream requests once the page fully loads, and one fixed reference can reveal another sitting behind it.

Preventing It on the Next Redesign

Before any future redesign or platform migration goes live, run the new site on a staging URL first and specifically check the browser console for mixed content warnings before pointing the live domain at it. It takes minutes and catches this exact problem before customers ever see a broken padlock. WebsNP's team checks for mixed content as a standard step whenever we handle a redesign or migration for a hosting client; if your site just relaunched and the padlock looks wrong, message our support team and we'll find every broken reference for you.