Migrating from Auto Unseal to Shamir seal

Hello!

I am trying to migrate from Auto Unseal(AWS KMS) to Shamir Seal. I have 3 Vault pods. For the first 2 pods, migration works well, but on the 3rd pod I see:

  1. Pod’s Logs: “core.autoseal: recovery seal configuration missing, but cannot check old path as core is sealed”
  2. when issuing the command: vault operator unseal - migrate key, I get:
URL: PUT http://127.0.0.1:8200/v1/sys/unseal
Code: 500. Errors:

* failed to obtain seal/recovery configuration
command terminated with exit code 2

If I insist with migration command, the migration works.
What can be the route cause?

Thank you,
Adrian