GreXXL serdo you are requiring a specific version of this plugin. You need to change it from a specific version to "*" in your composer.json.
GreXXL serdo I did not provide a command. You need to edit your composer.json fixing the required version by changing it from a fixed version to asterix. You can also post your composer.json content of you don’t know what to change.
davwheat This extension hasn't been updated yet, so installing it on a forum running B.16 or 1.0 will fail.
Justman10000 FriendsOfFlarum Outdated Root composer.json requires fof/mason 0.5.1 -> satisfiable by fof/mason[0.5.1]. fof/mason 0.5.1 requires flarum/core >=0.1.0-beta.15 <0.1.0-beta.16 -> found flarum/core[v0.1.0-beta.15] but it does not match your minimum-stability.
[deleted] Justman10000 did you see the incompatible tag for this extension ? It looks as though this may be abandoned
datitisev The Incompatible tag does not mean this extension is abandoned. It just hasn't been updated yet for v1. Looking at GitHub, it looks like it was updated (FriendsOfFlarum/mason9404279) but is going through some additional fixes/refactors.