Is there any way to update all Extensions with one command?

If you want to update major versions, then use the composer outdated -D command to see which extensions need updating and change the version manually in composer.json and then composer update -W . Unfortunately, there is no option to update with a single command.

    Hari I use

    composer update

    The command starts updating all extensions and Flarum core / laravel.

      Make sure that all extensions in the composer.json have * as value. The extiverse helper does the same thing, that would actually be the simplest way to upgrade. See https://extiverse.com/helper