Tableau dashboards can embed other non-Tableau webpages within them. This can be useful just as a way to show an external web page within your dashboard, or they can have dynamic URL parameters passed into them based on the data in your dashboard, meaning that you can produce interactive product catalogues, mapping systems and the like.
In Tableau Desktop you just drag a “Web page” part into your dashboard to do this.
You might find that the embed works nicely locally, so go on to publish it to Tableau Online (or perhaps Tableau Server). Then you go to review the published version and notice that it’s stopped working – you get a big blank space where you were expecting your embedded web page.
Do not panic – there’s often a simple solution. The URL you entered into the web part of your dashboard in Tableau Desktop probably started “http:” or with no http at all. Try changing it to use the secure “https” version of the website, i.e. https://whatever.com instead of http://whatever.com , republish your work and see if it fixes it up. I have had a 100% success rate with this.
If you search hard enough then the Tableau documentation does pretty much lead you to the answer, but it doesn’t seem like it’s common knowledge in a quick poll of my immediately-proximate Tableau users
(Personally I see this almost as a bug. If something renders fine on your desktop and appears to publish without incident to the server then you would expect it to look and work the same as your copy does. I would be happy to join a campaign such that you are prompted upon publishing that “your embedded web page will not work”. This is one of many reasons why it’s always a good idea to check your published workbook even if you are a million percent happy with the version your produced in Tableau Desktop.)