Для исправления следует залить новую версию. Взять можно на официальной странице SF.
Полное описание
NEED UPGRADING: NAS4Free below 247 have big problems.
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All version of NAS4Free below 247 have wrong input validations. Due to this, any user can insert invalid characters to NAS4Free. It's easy to destroy the system! 9.0.0.1.XXX have wrong config conversion at boot. It is failed until you touch "Access > Users and Groups".
Once the config is converted, it's impossible to recover. To avoid a security risk, all the previous versions were deleted from SF. NAS4Free 9.1.0.1.xxx is current developing version. And it should be base version for future releases. If your hardware is not compatible with 9.1, please use 9.0.0.1.249 or higher instead until a problem is fixed.