The "Huygen" upgrade guide (v0.6.* to v0.7.*) :

The Cronos v0.7.0 - Huygen upgrade is proposed to be scheduled at the block height of 2,693,800. Referencing estimated time can be found on https://cronoscan.com/block/countdown/2693800
DO NOT UPGRADE to the binary v0.7.0 before that suggested upgrade schedule.
You might check the current block height by the Cronoscan explorer or using
curl -s https://rpc-cronos.crypto.org:443/commit | jq "{height: .result.signed_header.header.height}"

Step 0 - Don't panic

At the point of the proposed upgrade, user will see the error message on the cronosd similar to the below:
ERR UPGRADE "v0.7.0" NEEDED at height: 2693800: {\"binaries\":{...."}}
Don't panic - The Chain will be paused to allow the majority of validators to upgrade. Validators and full node hosts will have to upgrade your Cronos nodes to the latest release binary.

Backups

Before the upgrade, node hosts are encouraged to take a complete data backup. backup depends heavily on infrastructure, but generally, we can do this by backing up the .cronos directory.
It is critically important for validator operators to back-up the .cronos/data/priv_validator_state.json file after stopping the cronosd process. This file is updated every block as your validator participates in consensus rounds. It is a critical file needed to prevent double-signing if the upgrade fails and the previous chain needs to be restarted.

Step 1 - Get the v0.7.0 binary

To simplify the following step, we will be using Linux-x86 for illustration. Binary for Mac Windows with different DB and architecture are also available here.
  • Terminate the cronosd; afterwards, download the 0.7.0 released binaries from github:
    $ curl -LOJ https://github.com/crypto-org-chain/cronos/releases/download/v0.7.0/cronos_0.7.0_Linux_x86_64.tar.gz
    $ tar -zxvf cronos_0.7.0_Linux_x86_64.tar.gz
Remarks: If you have stated cronosd with systemd service, kindly stop it by
$ sudo systemctl stop cronosd
And replace the binary in the location where the ExecStart states in Systemd Unit file.

Step 1.1 - Verify the version

You can verify the installation by checking the version of cronosd, the latest version is 0.7.0.
# check the version of cronosd
$ ./cronosd version
0.7.0

Step 1.2 - Update app.toml

In this v0.7.0 upgrade, there are a few extra parameters that we would have to add to .cronos/config/app.toml under
  • EVM Configuration - [evm] and;
  • JSON RPC Configuration - [json-rpc]. they are:
...
...
###############################################################################
### EVM Configuration ###
###############################################################################
[evm]
+ max-tx-gas-wanted=500000
...
...
###############################################################################
### JSON RPC Configuration ###
###############################################################################
[json-rpc]
+ feehistory-cap = 100
+ logs-cap = 10000
+ block-range-cap = 10000
+ http-timeout="30s"
+ http-idle-timeout="120s"
...
...
kindly insert the above parameters, save it and move on!

Step 2. - Run everything

We are ready to start the node join the network again with the new binary:
  • Start cronosd, e.g.:
$ ./cronosd start
Remark: Once the cronosd is started we would see the message
applying upgrade "v0.7.0" at height: 2693800"
and there will be an iteration over the previous blockchain data. This process will take a while, which is depending on the size of the database and the hardware specs.
Afterwards, sit back and wait for the syncing process. You can query the node syncing status by
$ ./cronosd status 2>&1 | jq '.SyncInfo.catching_up'
If the above command returns false, it means that your node is synced; otherwise, it returns true and implies your node is still catching up.
At this step, you've successfully performed the Huygen upgrade!