How do I install watchOS 26 on my Apple Watch Series 8?

The beta will be available in July. You’ll want to use it on a spare device, with data and apps and functions that you don’t need to work reliably, or to work. The released version of watchOS 26 will be available later this year.

Remember, that Beta watchOS versions can not be downgraded on your Apple Watch:

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To use a previously-released version of iOS, iPadOS, or macOS, you can restore your device from the backup that you created before installing the beta. Please note Apple Watch cannot be restored to previously-released OS versions once the beta is installed.

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copied from: Apple Beta — FAQ

JoseCastilloNavas wrote:

I meant watchOS 6 but it was a typo

watchOS 6 cannot be installed on Apple Watch Series 8.

Series 8 was first available with watchOS 9.

Any reset or re-pairing, and you’ll get watchOS 11. No downgrade.

For watchOS 26, and with the rest of the prerequisites mentioned in earlier replies, and with spare gear and a spare Apple Account, you’ll have to wait until next month.

I don’t think it’s available yet. Beta releases in July. I can’t wait for it either!!😃

WatchOS 26 will be available in the fall and will require an iPhone running iOS 26, which will also be available in the fall.