Do you constantly provision and delete Azure Key Vaults?
If so, you may have noticed attempts to recreate a recently deleted key vault will result in the following error:
The vault name is already in use. This is because Azure Key Vaults are kept in a deleted state and not automatically purged. You must manually purge these key vaults to be able to reuse the name.
To confirm the key vault in question is in “deleted” state, you can run the following: