Yes, you can go directly to 8.10.0.4 from 8.6.0.12. Start by upgrading the MMs, and then the Managed Device / Controllers. As explained with the backwards compatibility or "multi-version support", your MM can be on 8.10, and you can still manage 8.6, 8.7, 8.8, and 8.9. Usually its only supported to manage up to 3 revisions back, but Aruba extended this to 4 revisions back due to 8.6 being the last LSR.
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Dustin Burns
Lead Mobility Engineer @Worldcom Exchange, Inc.
ACCX 1271| ACMX 509| ACSP | ACDA | MVP Guru 2022
If my post was useful accept solution and/or give kudos
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