Installing problems

kupec

[RuntimeException]
Could not load package intervention/image in http://packagist.org: [UnexpectedValueException] Could not parse version constraint 4.x.x:
Invalid version string "4.x.x"

[UnexpectedValueException]
Could not parse version constraint 4.x.x: Invalid version string "4.x.x"

luceos

kupec How did you install Flarum? Can you explain more, this is really too little information to start assistance with.

Red

Run the following command from terminal.

composer self-update

then try again.

WaldemarHamm

Maybe you installed composer via apt-get? If composer self-update didn't work, then this is the reason.