TS-x31P/x31+ running QTS prior to 4.3.6.0895 build 20190328 will fail to upgrade to QTS 4.4.1 with the following system log Failed to update system. A flash read/write error occurred. Error code: FW004.
Please run following procedures to resolve this issue.
1. Download the latest QTS 18.104.22.1680 firmware from following link below or later version
2. Manually Upgrade TS-x31P/x31+ by web interface with above file.
3. After NAS reboots, run Live update to upgrade the firmware to 4.4.1 again.