This guidance assumes that the current running version of Vault is 2.7.x or higher.
The upgrade path recommended is to always upgrade to the last minor and patch of each Vault series, before upgrading to the next series. Currently, this is:
2.x.y → 2.8.13 → 3.3.11 → 4.5.4
If you hold a later patch or a later minor release, this can and should be used instead. At the time of writing, the latest 4.x Vault series version is Vault 4.6.0. If you are reading this and hold Vault 4.6.1 patch release, this means that the upgrade path should be 3.3.11 to 4.6.1 instead (if you are interested in the fixes contained within 4.6.1).
Upgrading to latest 2.x Vault series from 2.7.x