- Although version 56 is scheduled to "silently and forcibly auto-upgrade" users running the 32-bit version of Firefox on 64-bit computers with more than 2GB of RAM to the 64-bit version, it was not updated to the 64-bit version on my machine.
- Users of Lenovo's "OneKey Theater" software for IdeaPad laptops and users running Firefox for Windows over a Remote Desktop Connection (RDP) are advised to check the unresolved issues in the Release Notes.
- Version 56 makes Firefox Screenshots and Send Tabs available to all users.
- See the following regarding add-ons starting in Firefox 57: Firefox add-on technology is modernizing
Mozilla Firefox Release Notes