Ruby gemの互換性によりビルドが失敗しました

インストール
2

Somehow you have ruby 2.7.0 where I have ruby 3.2.0. Perhaps you could show your complete log - something has failed to be updated. The usual sequence is

cd /var/discourse
git pull
./launcher rebuild app

(although in your case, not app, but polyf)

In a nearby thread:

「いいね！」 4