ssh进入flarum目录执行以下命令:
sed -i "s#a-z0-9_-#-_a-z0-9\\x7f-\\xff#" \
vendor/flarum/core/src/Core/Validator/UserValidator.php
没有ssh的请自行修改文件
vendor/flarum/core/src/Core/Validator/UserValidator.php
将文件中
'regex:/^[a-z0-9_-]+$/i',
修改成
'regex:/^[-_a-z0-9\x7f-\xff]+$/i',