This page explains a known issue upgrading to Vault 1.1.2 for Enterprise users. Please read it carefully.
NOTE: This is a known issue applicable to Vault Enterprise.
During upgrades to 1.1.0, 1.1.1 or 1.1.2, Vault replication secondaries may require an automatically-triggered reindex, either if upgrading from a pre-0.8 version of Vault or if a previously-issued reindex operation has failed in the past. In these reindex scenarios, the secondary cluster will perform a complete WAL replay, which can take a long time and is a partially blocking operation.
This is fixed in Vault 1.1.3, and we recommend upgrading to Vault 1.1.3+ rather than any prior 1.1.x version. We also strongly recommend upgrading your Vault cluster to 1.1.3 if you are running Vault Enterprise 1.1.0, 1.1.1 or 1.1.2.