I don't understand you question. "When you upload the image", what? What happens? Do you see the BBcode but no the image?
matteocontrini Yes，I want it to show pictures
Carlosfengv delete storage/formatter contents: eg:
$ rm -rf storage/formatter/*
Still no effect，And show “ An error occurred while trying to load this page. ”
Did you already try to clear the cache with php flarum cache:clear?
php flarum cache:clear