After upgrading to CiviCRM 4.7.28 in WordPress, when users are trying to draft mailings in CiviMail using a template (which contains unsubscribe/opt out/resubscribe/subscribe tokens, the {domain.address} token, and URLs to our website and Facebook), when CiviMail tries to autosave the draft, the user gets this error message:
"Mailing has not been saved, Content maybe out of date, please refresh the page and try again"
This error does NOT occur when not using a template, but if you use a template when you start a message, and then delete it, the error does continue to occur. It seems like it's related to the template but I can't really understand why.
Anyone have any ideas on why this would be occurring and how to fix it?