Google Container-Optimized OS (COS) cos-121 End of Life
Support dates and upgrade guidance — rebuilt from live data.
Google Container-Optimized OS (COS) cos-121 is actively supported. It reaches end of life on 1 Mar 2027.
Support timeline
Official dates from the Google Container-Optimized OS (COS) release process.
| Milestone | Date | Status |
|---|---|---|
| Initial release | 14 Apr 2025 | — |
| End of life (scheduled) | 1 Mar 2027 | in 204 days |
| Latest release | cos-121-18867-528-43 · 4 Aug 2026 | current |
How much runway a newer branch buys
Moving to Google Container-Optimized OS (COS) cos-129 extends security support by about 366 days.
| Branch | End of life | Days left | vs cos-121 |
|---|---|---|---|
| Google Container-Optimized OS (COS) cos-129 | 1 Mar 2028 | 570 | +366 days |
| Google Container-Optimized OS (COS) cos-125 | 1 Sept 2027 | 388 | +184 days |
| Google Container-Optimized OS (COS) cos-121 | 1 Mar 2027 | 204 | this branch |
| Google Container-Optimized OS (COS) cos-117 | 1 Sept 2026 | 23 | -181 days |
Frequently asked questions
When does Google Container-Optimized OS (COS) cos-121 reach end of life?
Google Container-Optimized OS (COS) cos-121 reaches end of life on 1 Mar 2027 — 204 days from now. After that date it receives no security fixes.
Is Google Container-Optimized OS (COS) cos-121 still supported?
Yes. Google Container-Optimized OS (COS) cos-121 is currently maintained. Latest release: cos-121-18867-528-43, published 4 Aug 2026.
What happens when Google Container-Optimized OS (COS) cos-121 reaches end of life?
Security fixes stop. After 1 Mar 2027 this branch receives no further updates under standard support.
How long do I have to upgrade from Google Container-Optimized OS (COS) cos-121?
204 days. Moving to Google Container-Optimized OS (COS) cos-129 instead buys roughly 366 more days of security support.