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

When you load a page in the Optimizely Editor, you may see a warning at the top of the editor that reads: "We have loaded your site using compatibility mode — you can still edit your page, but some site functionality might be missing" or "You're in Compatibility Mode." This compatibility mode message means you may be encountering an issue with mixed content.


You can use the Optimizely desktop app instead of the browser app to avoid the compatibility mode issue (and take advantage of additional features like device emulation). Please note, if you are attempting to load gated content, site that requires a login, follow the steps listed in this article.

Compatibility mode is triggered when your browser's security settings block mixed content or keep insecure (HTTP) content from being loaded into the Optimizely Editor's secure (HTTPS) page. As a result, there are two ways you can avoid compatibility mode and prevent the Optimizely Editor from blocking insecure content:

What's compatibility mode?

In September 2013, Internet Explorer, Chrome and Firefox implemented a new default setting that blocks "active mixed content." This is a security feature to prevent secure (HTTPS) websites from being attacked. If an HTTPS page contains insecure (HTTP) content and that insecure content is “active” (e.g., JavaScript or CSS), the insecure active content can be intercepted, compromised, and used to glean data from the secure part of the page. To prevent this, these browsers use a default setting to block insecure (HTTP) content that's loaded into a secure (HTTPS) page or frame.

Resolving compatibility mode in Google Chrome browsers

Compatibility mode can be usually be resolved in a Google Chrome browser by clicking the red shield icon at the end of the URL address bar and loading "unsafe scripts" and reloading the page.

Screen Shot 2017-12-04 at 5.39.28 PM.png

If the shield icon is not present or if allowing "unsafe scripts" does not resolve compatibility mode, download the Optimizely Editor Assistant Chrome extension. Once the extension is successfully enabled on your Chrome browser, click on the extension and enable "Strip X-Frame-Options Header" and reload the page.


Disable browser security settings

One way to avoid compatibility mode is to disable your browser's security settings. Here are instructions (or links to instructions) for each browser.

Google Chrome for Mac or Linux
  1. Quit Chrome (if you have it open).
  2. Open Terminal.
  3. Type this command into Terminal to open a Chrome incognito window:

    /Applications/Google\\ Chrome --user-data-dir=/tmp/tempchrome --allow-running-insecure-content --incognito &
Using this command will allow mixed content to run in all tabs in the incognito window that opens. Use this incognito window only for Optimizely. Use another original instance of Chrome for all other web browsing.
Google Chrome for Windows
  1. Right-click the Chrome icon that you want to modify.
  2. Select Properties.
  3. In the Target field, add the command line flag after ‘chrome.exe’ as follows:

    chrome.exe --allow-running-insecure-content
  4. Click OK to save.
Use this Chrome shortcut only for Optimizely. Use another original instance of Chrome for all other web browsing.
Mozilla Firefox
Mixed content blocking in Firefox (scroll down to "Unblock mixed content" for instructions).
Internet Explorer
"Only secure content is displayed" notification in Internet Explorer 9 or later
As of Safari 9, all mixed content is blocked by default. If you're using Safari, you can only load HTTPS or compatibility mode pages into the Editor.
If you are having compatibility mode issues with Safari, we recommend using Chrome instead.

How insecure content triggers compatibility mode

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.

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.

The Optimizely Editor loads your site in compatibility mode when mixed content is blocked and the Editor cannot load all of the content on your page. This is when you see the warning "We have loaded your site using compatibility mode."

The compatibility mode warning advises you that an insecure site (your page) is being loaded inside a secure site (the Editor). Optimizely displays the warning in the main canvas of the Editor if we detect that mixed content is being blocked, although we may not always be able to detect this.

How compatibility mode affects your site

Compatibility mode means the Optimizely Editor will not display blocked mixed content. When the Optimizely Editor loads your site in compatibility mode, some styling and content may not display correctly in the Editor. Content in iFrames may not render in the Editor.

The compatibility mode warning only affects the content displayed in the Optimizely Editor, not your live site.

Troubleshoot other page-loading issues