This article will help you:
  • Figure out why pages might not load in the Editor
  • Get rid of the "Compatibility Mode" dialog that appears in the Editor
  • Troubleshoot mixed-content issues

Is your page not loading correctly in Optimizely for another reason? Check our article on Editor Loading for more solutions!

When you load a page in the Optimizely Editor, you may see a warning that reads: "We have loaded your site using compatibility mode — you can still edit your page, but some site functionality might be missing."

If you see a message, "We have loaded your site using compatibility mode," you may be encountering an issue with mixed content.

Optimizely Editor loads your site in compatibility mode when it's not able to load all of the content on your page. As a result, some styling and content may not display correctly, and content in iFrames may not render in the Editor. If you have insecure (HTTP) content being loaded into a secure (HTTPS) page or frame, it may be blocked. 


This warning only affects the Optimizely Editor, not your live site.


Your browser's security settings may block mixed content, or insecure (HTTP) content being loaded into a secure (HTTPS) page or frame like the Optimizely Editor. If you don't want to disable your browser's security settings, the only way to ensure that your content is not blocked is to load your page securely via HTTPS.

How compatibility mode works

In September 2013, Internet Explorer, Chrome and Firefox implemented a new default setting that blocks "active mixed content." This is a security feature that prevents secure (HTTPS) websites from being attacked. If an HTTPS page has insecure (HTTP) content inside of it and that content is “active” (i.e. JavaScript or CSS), then the insecure active content can be intercepted, compromised, and used to glean data from the secure (HTTPS) part of the page. 

Why does this affect how Optimizely Editor loads sites?

If an insecure (HTTP) site that you load into the Optimizely Editor is compromised, it can compromise your Optimizely account. Optimizely’s Editor is always loaded securely via HTTPS to protect your experiments and data.

When loading your site, Optimizely will attempt to load both HTTP and HTTPS versions of the page; if both of these fail, we will attempt to load your website through our proxy server. We will prefer the HTTPS version of the site to the HTTP version if no protocol is specified. If you wish to load only the HTTP version, make sure to include the full URL (i.e. when you create the experiment.

If you try to load an insecure site into the Optimizely Editor (for example, instead of, your browser may trigger a mixed content warning and block the insecure site from loading. This is because the Optimizely Editor’s protocol is HTTPS, and the page you’re trying to load is HTTP. 

Note that the browser warning is meant only to advise you that an insecure site (your page) is being loaded inside a secure site (the Editor). Optimizely will show a message in the main canvas of the Editor if we detect that mixed content is being blocked, though we may not always be able to detect this: 

Troubleshoot other page-loading issues