A few specific websites do not load a "Highlight" image [Affected versions]: - Firefox 57 and up [Affected Platforms]: - All Windows - All Mac - All Linux [Prerequisites]: - Have a profile with enough history that all the "Top Sites" are populated. [Steps to reproduce]: 1. Open the browser with the profiles from prerequisites. 2. Navigate to https://mibbit.com/?server=irc.mozilla.org&channel=%23nightly. 3. Add the website to the bookmarks. 4. Observe the "Highlight" card of the previously bookmarked page. [Expected result]: - After a short while, a screenshot is displayed in the card. [Actual result]: - No image is displayed. [Notes]: - The issue is also reproducible with PDFs and images from google drive (e.g. https://drive.google.com/file/d/0B4PpDEhzmb-7QTVrNy1HTkgyRkE/view ). However sometimes the screenshot related to a PDF is displayed in the "Highlight" card after a long while or after a restart. - Attached a screenshot of the issue.

https://github.com/mozilla/activity-stream/issues/3509 has some screenshots of other sites that failed to screenshot (and end up showing a letter for top sites)