TL;DR: Azure Local 2601 and 2602 are no longer available as update targets — update to 2603 or later instead. If you are already running 2601 or 2602, you are unaffected and remain fully supported.
Recommended action:
Pick the path that matches your current version and discover/apply the corresponding solution version (or newer):
On 2510–2512, 2601, or 2602 → discover and apply solution version 12.2603.1002.502 or later.
On 2603 → discover and apply solution version 12.2604.1003.1006 or later.
On 2604 → discover and apply solution version 12.2605.1003.210.
Why:
Microsoft removed 2601 and 2602 as update targets so that clusters update into a build carrying the automated remediation for an issue that could cause unintended VM deletion. Hotfixes for 2603 and 2604 add that remediation as you update into them, which is why those (and later) are the supported targets. Solution and SBE updates have resumed now that this is in place.
Going forward:
Treat 2603 as the minimum update target from here on. If you are mid-migration of a cluster still pointed at 2601/2602 as a target, repoint to 2603 or later before proceeding.
Optional details:
For the 2510 servicing line, builds 11.2510.1002.93 and 12.2510.1002.531 (which supersedes 12.2510.1002.529) are available. Upgrade paths: from 11.2510.1002.87 you can go directly to 12.2510.1002.531; from an earlier build, update to 11.2510.1002.93 first, then to 12.2510.1002.531; and from 12.2509.1001.22 you can update to 12.2510.1002.94.
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