Troubleshoot: Pages not loading in the Editor

  • Updated

This topic describes how to:

  • Figure out why a page isn't loading in the Editor
  • Diagnose and fix common editor-loading issues
  • Clear your browser cache and cookies

Are you seeing a message in the Editor: "Sorry, we were unable to load..."? Or having trouble accessing a certain page in the Editor? Maybe you see something that looks like this:

If pages are not loading in the Editor the way you expect, this article will help you troubleshoot.

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

  • If you are trying to load content that's in an iframe, read about loading iframe content.

  • If the issue is loading pages that require session-specific information or logging in (like a shopping cart, intranet page, or password-protected content), check out this troubleshooting article.

If you are seeing a different problem, keep reading to troubleshooting and resolve issues with page-loading in the Optimizely Experimentation Editor.

The Optimizely Experimentation Desktop App solves many common Editor loading issues, including those listed here. Consider installing it if you are having trouble with the web application.

Common Editor page-loading issues

Try these steps, one by one, to try to resolve some common page-loading issues.

  1. Confirm that your page loads consistently outside of Optimizely Experimentation. Make sure you can reach the page in your browser, outside of Optimizely Experimentation, multiple times in a row. If the page does not load outside of Optimizely Experimentation, it may not load in Optimizely Experimentation either.

  2. Clear your browser cache and cookies. Then, reload the page.

  3. Confirm that the Optimizely Experimentation snippet is installed: open the developer console and type optimizely. If the search returns an error, such as "optimizely is undefined," the snippet is not implemented correctly.

    Here is how to implement the snippet for Optimizely Web Experimentation. Make sure the snippet is installed synchronously at the top of your <head> tag.

  4. Try loading the page via the Pop-out Editor.

Advanced Editor page-loading issues

Here are more steps to try when the steps to resolve common issues are not successful:

  1. Check the JS console for errors that do not normally exist on the page. Filter the console output for error logs. If you see an error within bundle or client.js/[projectID].js, there may be a conflict. If your site is using Content Security Policies, the error will begin with: refused to execute inline script because it violates the the following Content Security Policy. In some scenarios, you can use a browser extension to get around this issue.

  2. Confirm whether your site is configured to disallow parameters it does not expect and parameters that include raw URLs.
    To check this, try to load the page with an innocuous query parameter like ?test=true and then a parameter that contains a raw URL.
    If your site disallows unexpected parameters, you need to whitelist Optimizely Experimentation's Editor parameters. Contact support to learn more or try the Optimizely Experimentation Desktop App.

  3. Check whether the page loads outside the Editor within an arbitrary iframe.
    Some sites have frame-busting logic that prevents them from being iframed correctly. Try constructing an iframe on any page through the browser console to see if the page loads correctly. Here is an example:

<iframe src='' style='width:800px;height:600px'></iframe>

If the page will not load in an arbitrary iframe, you may need to whitelist the Optimizely Experimentation domain ( as a valid host. Or, try the Optimizely Experimentation Desktop App.

If you tried the steps in this article, but still cannot correctly load your page in the Editor, try our Optimizely Experimentation Editor loading Chrome extension.