Live preview option not working for multi-site functionality I am working on a site which has the multisite concept. Each site has its own base URL. The issue is that, if I have logged in to the admin with the primary site and access the preview option for the secondary site in the system then it is showing the cross-domain error in the console of the browser.

Is there any way to solve the issue?
Essentially you're looking for this feature request: https://github.com/craftcms/cms/issues/1160

That has been resolved in https://github.com/craftcms/cms/commit/1ab6b6e6e3cd5a13c949d113c8367e7faf930ee4 which will be released in Craft 3.1.