12 ‐ Encrypt Boot volume with Custom managed keys - SanjeevOCI/Ocidocs GitHub Wiki
Navigate to Burger Menu --> Storage --> Boot Volumes --> Select the Boot Volume --> Click on Encryption Key --> Assign
The above error indicates that the KMS key doesn't has the right permissions. In order to assign the encryption key to the Boot Volume, we need to create a policy to allow the Block Storage to use keys in the compartment(computecompartment) where the vault is located.
Now that the policy has been created, we are able to assign the Encryption keys to the Boot volume