Mozilla/5.0 (X11; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0 ID:20170521100319 CSet: 5b74bbf20e803e299790d266fc6ebf5d53b7a1b7 This week, I have noticed weird behaviour in nightly. I have about 5 tabs open. When I load some of the tab for the first time after few tenths of minutes after Firefox is started, the content loads (i.e. is shown in DevTools), but does not display. Even after Ctrl+F5, only a white page is visible (Tab Center displays black rectangle as a thumbnail). No errors are shown in the browser console. As this affects multiple tabs at the same time, I suspect this is some glitch with one of the content processes, maybe because I have set to reload the tab content after it is selected, not immediately after Firefox starts. Restarting Firefox helps. STR: 1. Start Firefox with few tabs from the previous session. 2. Browser for a longer time, but do not open the restored tabs. 3. After some time, click one of the tabs. 4. Content is loaded, but not displayed.

Killing the corresponding process and reloading the tab again also helps.

OK, now I have caught some output in the console, but I am not sure, if it's related to this particular behaviour.

Maybe it's related to bug 1362378?

This sounds an awful lot like bug 1364563.

I haven't noticed this bug for quite some time.