Chrome Extension Manifest V2 will eventually die. When that happens, everyone will probably need to replace some of their MV2 extensions with an MV3 alternative. For Maximize All Windows, I've already released a similar extension for MV3 (link below). It may or may not work exactly the same way. Sorry for any inconveniences (blame Google). https://chromewebstore.google.com/detail/maximize-windows/oealklhjfdmeafmhkmgjplhlldkiblge?authuser=2&hl=en . . . Maximizes all windows belonging to the current browser. Features: An option for controlling whether addon maximizes windows on browser startup. An option for controlling whether addon maximizes new windows when they are created. An option for controlling whether windows are minimized if they were minimized before maximizing. Have ideas for new Addons? Send me an email, I love talking about new ideas!