We have had a strange issue on a live site.
Every now and again, when someone clicks the “Save and Preview” button on a content page, the new tab opens and the user either gets a generic 503 error or this :
But you can still go back to the content editing tab and carry on using the CMS as normal. Once this has happened, all previews result in this page shown above (or a 503).
The only way to fix this for the client is they logout and back into the CMS
Any ideas ? (its driving us nuts)
This is a companion discussion topic for the original entry at https://our.umbraco.com/forum/113574-preview-sometimes-stops-working