Troubleshooting Issues Related to the Visual Experience Composer and Enhanced Experience Composer

Display problems and other issues sometimes occur in the Adobe Target Visual Experience Composer (VEC) and the Enhanced Experience Composer (EEC) under certain conditions.

How do the recently announced Google Chrome SameSite cookie enforcement policies impact the VEC and EEC?

With the latest changes (August 2020), all users with Chrome 80+ browser versions:

  • Will not be able to use the VEC (with or without the VEC Helper extension installed and enabled) in password-protected pages of their sites. This is because their site login cookie(s) will be considered a 3rd-party cookie and will not be sent with the login request. The only exception is when the customer site login cookie already has the SameSite parameter set to “none.”
  • Will not be able to download Target libraries while editing an activity (when these aren’t already on the site). This is because the download call is made from the customer domain towards a secured Adobe domain and is rejected as unauthenticated.
  • The EEC will not function for all users because it is not able to set the SameSite attribute for cookies on domain. Without this attribute, the browser will reject these cookies, causing the EEC to fail.

Adobe has submitted an updated VEC Helper extension to the Google Chrome Store. This extension overwrites the cookie attributes to set the SameSite="none" attribute, when needed. The updated extension can be found here. For more information about installing and using the VEC Helper Extension, see Visual Experience Composer helper extension.

For your own site cookies, you must specify the cookies by name. Toggle the Cookie slider to the on position, then specify the cookie by name and the cookie domain. The cookie name is “mbox” and the cookie domain is the second and top levels of the domains from which you serve the mbox. Because it is served from your company’s domain, the cookie is a first party cookie. Example: For more information, see Adobe Target Cookies in the Experience Cloud Interface User Guide.

Cookies toggle in the VEC helper extension

Alternatives and workarounds

Use one of the following options to ensure that your VEC and EEC continue to work as expected:

  • Download and use the updated VEC Helper extension.

  • Use the Mozilla Firefox browser. Firefox is not yet enforcing this policy.

  • Continue to use Chrome, but set the chrome://flags/#same-site-by-default-cookies flag to “Disabled."


    This will not be enough if cookies already have the SameSite attribute set to “Lax” or “Strict” from the server.

Does Target support multi-level iframes?

Target does not support multi-level iframes. If your website loads an iframe that has a child iframe, Target libraries (at.js and mbox.js) interact with the parent iframe only. Target libraries do not interact with the child iframe.

As a workaround, you can add a page in the experience with the URL of the child iframe.

When I try to edit a page, all I see is a spinner instead of my page. (VEC and EEC)

This can happen if the URL contains a # character. To fix the issue, switch into Browse mode in the Visual Experience Composer, and then switch back to Compose mode. The spinner should go away and the page should load.

Content Security Policy (CSP) headers block the Target libraries on my website. (VEC and EEC)

If your website’s CSP headers block Target libraries, then loads the website but prevents editing, ensure that the Target libraries are not blocked.


In addition to the following information, you can use the Adobe Target VEC Helper browser extension for Google Chrome.

As a workaround, you can configure a Requestly rule to remove CSP headers, as shown below:

You can configure a similar Requestly rule for any header that causes a resource to not load inside the VEC.

For Requestly, whenever there is a need to remove headers, you should do either of following:

  • Add URL rules for the URL that you want to open in the VEC so that headers are removed for those URLs only.
  • Enable the rule when you are editing in the VEC and disable the rule when you are not using the VEC.

The VEC or EEC appears broken or does not initialize when re-editing a saved activity. (VEC and EEC)

If the website has changed outside of the Visual Experience Composer after the experience was defined, selectors on which actions were taken earlier cannot be found when the activity is opened for re-editing. The page appears broken, and no warning displays.

The VEC or EEC does not show my rotating banners and other content containing JavaScript. (VEC and EEC)

By default, the Visual Experience Composer blocks JavaScript elements. You can work with these elements if you disable JavaScript in the Visual Experience Composer settings. Depending on how the site is set up, some items might continue to display incorrectly or to remain unavailable.

My hosted target.js file fails to load on subsequent page reloads. (VEC and EEC)

This issue happens when customers have an mbox.js version earlier than 57 (i.e. version 56 or earlier).

We recommend that all VEC users upgrade to the latest version of mbox.js, or at least upgrade to version 57. You should also consider making the transition to at.js.

When I change one element on the page, multiple elements change. (VEC and EEC)

If the same DOM element ID is used on multiple elements on the page, changing one of those elements changes all elements with that ID. To prevent this from happening, an ID should be used only once on each page. This is a standard HTML best practice. For more information, see Page Modification Scenarios.

I can’t edit experiences for an iFrame-busting site. (VEC and EEC)

This issue can be addressed by enabling the Enhanced Experience Composer. Click Administation > Visual Experience Composer, then select the check box that enables the Enhanced Experience Composer. The Enhanced Experience Composer uses an Adobe-managed proxy to load your page for editing. This allows editing on iFrame-busting sites and allows editing on sites and pages where you have not yet added Adobe Target code. The activities do not deliver to the site until the code has been added. Some sites may not load via the Enhanced Experience Composer, in which case you can uncheck this option to load the Visual Experience Composer via an iFrame. []


Your locally hosted pages or pages that are not accessible outside your network are not accessible to the Adobe proxy server and cannot be opened in the EEC. These pages might include staging URLs, User Acceptance Testing (UAT) URLs, or locally hosted pages.

I want to set up tests on pages that don’t have the mbox/target implementation done yet. (VEC and EEC)

See “I can’t edit experiences for an iFrame-bursting site” above.

Bold and italic text styles with Edit Text/HTML or Change text/HTML do not show on my page. Sometimes the text disappears after applying these style changes. (VEC and EEC)

If you use Edit Text/HTML in the Visual Experience Composer for A/B or Experience Targeting activities or Change Text/HTML for Automated Personalization or Multivariate Test activities to make text bold or italic, those styles might not be applied on the page or the text disappears from the page in the Visual Experience Composer. This is because the way the rich-text editor applies these styles might interfere with the website markup.

If you see this issue:

  1. Click the HTML button in the rich-text editor to enter source editing mode.

  2. Find the styles text elements.

    • For bold text, change <strong> elements to <b>.

    • For italic text, change <em> elements to <i>.

For Automated Personalization activities, image swapping appears broken in the VEC or EEC. (VEC and EEC)

Adding an image offer to a location takes the full dimension of the original image space in the VEC or EEC. On delivery, the image is not expanded and is shown as it is, so there is no impact on delivery.

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