watchOS 26
Как сделать откат с watchOS 26 на предыдущую версию?
Apple Watch SE (2nd generation)
Sorry, but after installing a Beta version of watchOS, you can not go back to the latest official firmware. You will have to wait until a public version has been released by Apple and continue using watchOS26 in that case.
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How do I restore a prior shipping release of iOS, iPadOS, macOS, tvOS, HomePod software or watchOS?
Always back up your iPhone, iPad or Mac before installing the beta. Since Apple TV, HomePod mini, and HomePod (2nd generation) data and purchases are stored in the cloud, there’s no need to back up your devices. 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