The cause of the problem is the modern cache backend implemented in Firefox Nightly. It is designed to improve the stability and performance of the Firefox process, and eliminate craches and hangs caused by the older cache implementation. However, it still has issues. For example, if you try to play an HTML5 video on YouTube, you will get only a black screen.
To fix the issue, you need to do the following:
- Open a new tab and enter the following text in the address bar:
Confirm that you will be careful if a warning message appears for you.
- Enter the following text in the filter box:
- Now restart Firefox Nightly
It is a good idea to keep the new cache feature disabled until Mozilla fixes this issue. At this moment, Mozilla is working on a solution for this issue.