TerraMaster TOS 4.x End-of-Life (EOL) Announcement
Posted: 27 Apr 2026, 10:08
Dear TerraMaster Users,
Thank you for your continued trust and support of TerraMaster products. To provide users with a more secure, efficient, and intelligent storage experience, and in light of the maturity of TOS 6 and the ongoing beta development of TOS 7, we hereby officially announce that TOS 4.x will reach End-of-Life (EOL) and cease all maintenance services as of May 1, 2026.
I. Key Reasons for Discontinuation
1. Aging Technical Architecture: TOS 4.x was released nearly 10 years ago. Its underlying architecture is based on an earlier Linux kernel, which is no longer well-suited for modern hardware and technologies such as NVMe high-speed storage, multi-network port aggregation, and TRAID. It also has clear limitations in terms of compatibility with next-generation network protocols and security standards.
2. Imbalance Between Maintenance Costs and Risks: Due to the outdated codebase of TOS 4.x, maintaining the system requires significant resources to keep up with evolving security requirements. Meanwhile, patching an aging architecture may introduce compatibility issues and increase system instability risks.
3. Inevitable System Evolution: TOS 6 introduces over 40 new features and more than 370 enhancements, powered by Linux Kernel 6.1 LTS. It delivers significant improvements in data security (SPC security control, TRAID+ dual-drive redundancy), user experience (tabbed file management, dynamic UI), and performance (SMB multichannel, dedicated system disk). The upcoming TOS 7 will further integrate intelligent management features. To focus resources on innovation, we must discontinue support for legacy systems.
II. Impact of Discontinuation
Starting May 1, 2026, TOS 4.x will no longer receive maintenance services. As a result, the following risks may arise:
1. No Security Updates: Newly discovered vulnerabilities, malware, and ransomware threats will not be patched, posing significant risks when connected to the internet.
2. Termination of Technical Support: TerraMaster will no longer provide technical support for TOS 4.x, including troubleshooting, consultations, and remote assistance.
III. Recommendations and Actions
To ensure your data security and user experience, we strongly recommend taking the following actions:
(1) Prioritize Upgrading to TOS 6
1. Visit the official forum to check whether your device supports upgrading to TOS 6.
2. Back up all important data via external drives or cloud services before upgrading.
3. Supported system versions by model series:
Maximum TOS 4.x:
210 Series: F2-210, F4-210
Recommended TOS 5.x:
220/420 Series: F2-220, F4-220, F5-220, F2-420, F4-420, F5-420
420 Series: U8-420, U12-420, U16-420
Recommended TOS 6.x:
221/421/422 Series: F2-221, F4-221, F5-221, F2-421, F4-421, F5-421, F4-422, F5-422
(Note: Models manufactured on or before June 2020 do not support upgrading to TOS 6)
223/423 Series: F2-223, F4-223, F2-423, F4-423, T6-423, T9-423, T12-423, U4-423, U8-423
450 Series: T9-450, T12-450, U8-450
424 Series: F2-424, F4-424, F4-424 Pro
Others: U8-522-9400, U8-722-2224, U16-722-2224, U16-722-2278, U24-722-2224, U24-722-2244
(2) Upgrade Your Hardware if TOS 6 Is Not Supported
If your device cannot upgrade due to hardware limitations, we recommend replacing it with a new TerraMaster NAS device:
1. New devices support TOS 6 by default with better performance, capacity, and security.
2. Data migration while retaining existing drives and data is supported under certain conditions:
- Choose a NAS with more drive bays or additional M.2 slots
- Use extra slots for TOS 6 installation
- Install TOS 6 on new drives, then contact support for migration assistance
3. Trade-in Program:
From May 1 to August 31, 2026, TOS 4.x users can receive official discounts when upgrading. Contact support or visit the official website for details.
IV. Support and Contact
Thank you again for your understanding and support. TerraMaster remains committed to data security and will continue to deliver reliable and intelligent storage solutions.
For inquiries, please contact us via:
- Official online support
- Official forum
- Email: support(at)terra-master.com
TerraMaster Product Team
April 27, 2026
Thank you for your continued trust and support of TerraMaster products. To provide users with a more secure, efficient, and intelligent storage experience, and in light of the maturity of TOS 6 and the ongoing beta development of TOS 7, we hereby officially announce that TOS 4.x will reach End-of-Life (EOL) and cease all maintenance services as of May 1, 2026.
I. Key Reasons for Discontinuation
1. Aging Technical Architecture: TOS 4.x was released nearly 10 years ago. Its underlying architecture is based on an earlier Linux kernel, which is no longer well-suited for modern hardware and technologies such as NVMe high-speed storage, multi-network port aggregation, and TRAID. It also has clear limitations in terms of compatibility with next-generation network protocols and security standards.
2. Imbalance Between Maintenance Costs and Risks: Due to the outdated codebase of TOS 4.x, maintaining the system requires significant resources to keep up with evolving security requirements. Meanwhile, patching an aging architecture may introduce compatibility issues and increase system instability risks.
3. Inevitable System Evolution: TOS 6 introduces over 40 new features and more than 370 enhancements, powered by Linux Kernel 6.1 LTS. It delivers significant improvements in data security (SPC security control, TRAID+ dual-drive redundancy), user experience (tabbed file management, dynamic UI), and performance (SMB multichannel, dedicated system disk). The upcoming TOS 7 will further integrate intelligent management features. To focus resources on innovation, we must discontinue support for legacy systems.
II. Impact of Discontinuation
Starting May 1, 2026, TOS 4.x will no longer receive maintenance services. As a result, the following risks may arise:
1. No Security Updates: Newly discovered vulnerabilities, malware, and ransomware threats will not be patched, posing significant risks when connected to the internet.
2. Termination of Technical Support: TerraMaster will no longer provide technical support for TOS 4.x, including troubleshooting, consultations, and remote assistance.
III. Recommendations and Actions
To ensure your data security and user experience, we strongly recommend taking the following actions:
(1) Prioritize Upgrading to TOS 6
1. Visit the official forum to check whether your device supports upgrading to TOS 6.
2. Back up all important data via external drives or cloud services before upgrading.
3. Supported system versions by model series:
Maximum TOS 4.x:
210 Series: F2-210, F4-210
Recommended TOS 5.x:
220/420 Series: F2-220, F4-220, F5-220, F2-420, F4-420, F5-420
420 Series: U8-420, U12-420, U16-420
Recommended TOS 6.x:
221/421/422 Series: F2-221, F4-221, F5-221, F2-421, F4-421, F5-421, F4-422, F5-422
(Note: Models manufactured on or before June 2020 do not support upgrading to TOS 6)
223/423 Series: F2-223, F4-223, F2-423, F4-423, T6-423, T9-423, T12-423, U4-423, U8-423
450 Series: T9-450, T12-450, U8-450
424 Series: F2-424, F4-424, F4-424 Pro
Others: U8-522-9400, U8-722-2224, U16-722-2224, U16-722-2278, U24-722-2224, U24-722-2244
(2) Upgrade Your Hardware if TOS 6 Is Not Supported
If your device cannot upgrade due to hardware limitations, we recommend replacing it with a new TerraMaster NAS device:
1. New devices support TOS 6 by default with better performance, capacity, and security.
2. Data migration while retaining existing drives and data is supported under certain conditions:
- Choose a NAS with more drive bays or additional M.2 slots
- Use extra slots for TOS 6 installation
- Install TOS 6 on new drives, then contact support for migration assistance
3. Trade-in Program:
From May 1 to August 31, 2026, TOS 4.x users can receive official discounts when upgrading. Contact support or visit the official website for details.
IV. Support and Contact
Thank you again for your understanding and support. TerraMaster remains committed to data security and will continue to deliver reliable and intelligent storage solutions.
For inquiries, please contact us via:
- Official online support
- Official forum
- Email: support(at)terra-master.com
TerraMaster Product Team
April 27, 2026