General

Preview Problems and Third Party Cookies

What is this support document about

If you can’t preview your posts, pages, or themes on your blog – you may need to enable third-party cookies in your web browser.

Checking your browser…

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What are cookies?

Cookies, more specifically known as HTTP cookies or Browser Cookies, are small bits of information sent from a web server to a user’s web browser to save some information.

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How are they used on WordPress.com?

The main use of cookies on WordPress.com is to store your log in information – so that you don’t have to log in every time you visit the site.
Cookies are always attached to a domain – on WordPress.com it’s, well – wordpress.com.

So what’s the issue then?

When you have your own custom domain for your site, the cookie used to store your log in information becomes a third-party cookie, because while the cookie originates from the ‘wordpress.com’ domain, your browser is asked to read it when you visit your own domain.

As an example, let’s assume the following:

  • Your dashboard URL is yourawesomeblog.wordpress.com/wp-admin/
  • Your site url is yourawesomeblog.com

When you try to preview a draft post you are editing, we’ll open a new window with the draft post on your site. That window address will be something like http://yourawesomeblog.com/?p=xxxx&preview=true

Since you must be logged in to see draft posts, WordPress.com asks your browser for the log in cookie.
Because the preview page comes from the yourawesomeblog.com domain, and the log in cookie is from the wordpress.com domain, browsers that don’t have third-party cookies enabled will not send the required information, and the preview won’t work.

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How do I enable third-party cookies?

If you would like to enable third party cookies for just WordPress.com you will need to allow third-party cookies  (sometimes called setting an exception) from the following domains.

  • wordpress.com
  • yourawesomeblog.wordpress.com (where the “yourawesomeblog” part is your full WordPress.com site name)

Note, if you have a custom domain, for example yourawesomeblog.com you will also need to allow cookies from that domain making a total of three exceptions.

Alternatively you can enable third party cookies for all sites. In doing so you will not need to add any exceptions.

Check out the following links for instructions relevant to the web browser you use:

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I heard third party cookies are bad

There are some valid concerns about third party cookies and privacy. You can read more about it on Wikipedia. If you’re concerned, the instructions above will also help you enable third party cookies specifically for your own domain and WordPress.com.

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