TerraMaster Official Forum

Applicable model: F2-220、F2-221、F2-420、F2-421、F4-220、F4-221、F4-420、F4-421、F5-220、F5-221、F5-420、F5-421、F8-421

Because of the big difference between TOS3.X, TOS4.0 and TOS4.1, your current TOS version could not be updated to the latest directly.
Please manually update your TOS one by one as following:
Current version is below 3.1.15, please update to TOS3.1.5 --> 4.0.09 --> 4.1.03-->4.1.27--> 4.1.30;
Current version is 4.0.x, please update to 4.1.03-->4.1.27--> 4.1.30 .

Download link:
TOS3.1.15: https://dl.terra-master.com/cn/TOS_S1.0 ... _VN108.bz2
TOS4.0.09: https://dl.terra-master.com/cn/TOS_S2.0 ... _VN178.bz2
TOS4.1.03: http://dl.terra-master.com/cn/TOS_S2.0_ ... 03_294.bz2
TOS4.1.27: http://dl.terra-master.com/cn/TOS_S2.0_ ... 301433.bz2
TOS4.1.30: http://dl.terra-master.com/cn/TOS_S2.0_ ... 061157.bz2

Notes:
It's suggested to backup your data before updating your TOS (especially from TOS3.X). The installed apps should be reinstalled after TOS update (to TOS4.1).
Please go to TOS Control panel - privileges- shared folders- advanced to restore your folders if your files/folders are not visible after TOS update.
The update process would stay at 73% for about 10 minutes when updating to TOS 4.1.03, please do not refresh the page.