---
layout: docs
page_title: Upgrading to Latest 1.8.x
description: >-
  Specific versions of Consul may have additional information about the upgrade
  process beyond the standard flow.
---

# Upgrading to Latest 1.8.x

## Introduction

This guide explains how to best upgrade a multi-datacenter Consul deployment that is using
a version of Consul >= 1.6.9 and < 1.8.19 while maintaining replication. If you are on a version
older than 1.6.9, please follow the link for the version you are on from [here](/consul/docs/upgrading/instructions).

In this guide, we will be using an example with two datacenters (DCs) and will be
referring to them as DC1 and DC2. DC1 will be the primary datacenter.

## Requirements

- All Consul servers should be on a version of Consul >= 1.6.9 and < 1.8.19.

## Assumptions

This guides makes the following assumptions:

- You have at least two datacenters configured and have ACL replication enabled. If you are
  not using multiple datacenters, you can follow along and simply skip the instructions related
  to replication.

## Considerations

There are not too many major changes that might cause issues upgrading from 1.6.9, but notable changes
are called out in our [Specific Version Details](/consul/docs/upgrading/upgrade-specific#consul-1-8-0)
page. You can find more granular details in the full [changelog](https://github.com/hashicorp/consul/blob/main/CHANGELOG.md#183-august-12-2020).
Looking through these changes prior to upgrading is highly recommended.

## Procedure

**1.** Check replication status in DC1 by issuing the following curl command from a
consul server in that DC:

```shell-session
$ curl --silent --header "X-Consul-Token: $MASTER_TOKEN" "localhost:8500/v1/acl/replication?pretty"
```

You should receive output similar to this:

```json
{
  "Enabled": false,
  "Running": false,
  "SourceDatacenter": "",
  "ReplicationType": "",
  "ReplicatedIndex": 0,
  "ReplicatedRoleIndex": 0,
  "ReplicatedTokenIndex": 0,
  "LastSuccess": "0001-01-01T00:00:00Z",
  "LastError": "0001-01-01T00:00:00Z"
}
```

-> The primary datacenter (indicated by `primary_datacenter`) will always show as having replication
disabled, so this is normal even if replication is happening.

**2.** Check replication status in DC2 by issuing the following curl command from a
consul server in that DC:

```shell-session
$ curl --silent --header "X-Consul-Token: $MASTER_TOKEN" "localhost:8500/v1/acl/replication?pretty"
```

You should receive output similar to this:

```json
{
  "Enabled": true,
  "Running": true,
  "SourceDatacenter": "dc1",
  "ReplicationType": "tokens",
  "ReplicatedIndex": 672,
  "ReplicatedRoleIndex": 1,
  "ReplicatedTokenIndex": 677,
  "LastSuccess": "2020-09-14T17:06:07Z",
  "LastError": "2020-09-14T16:53:22Z"
}
```

**3.** Upgrade the Consul agents in all DCs to version 1.8.19 by following our [General Upgrade Process](/consul/docs/upgrading/instructions/general-process).

**4.** Confirm that replication is still working in DC2 by issuing the following curl command from a
consul server in that DC:

```shell-session
$ curl --silent --header "X-Consul-Token: $MASTER_TOKEN" "localhost:8500/v1/acl/replication?pretty"
```

You should receive output similar to this:

```json
{
  "Enabled": true,
  "Running": true,
  "SourceDatacenter": "dc1",
  "ReplicationType": "tokens",
  "ReplicatedIndex": 672,
  "ReplicatedRoleIndex": 1,
  "ReplicatedTokenIndex": 677,
  "LastSuccess": "2020-09-14T17:15:16Z",
  "LastError": "0001-01-01T00:00:00Z"
}
```

## Post-Upgrade Configuration Changes

No configuration changes are required for this upgrade.
