Table of contents


This article is a simple guide on how to get started mining Kulupu.

Import or generate a mining key

Kulupu implements signed mining. To mine Kulupu blocks, you have to have the coinbase private key stored in the mining software, as a new signature is produced for every new nonce. We refer to the private key for signed mining as the mining key.

The eaiest way to get a mining key is to generate a new one using the generate-mining-key command:

kulupu generate-mining-key

Keep your secret seed in a secure place.

Alternatively, you can also import an existing private key as the mining key, using the import-mining-key command:

kulupu import-mining-key "<secret seed>"

Pass author argument to node for mining

Remember either the public key or the address, and pass it to node for mining. For example:

kulupu --validator --author <coinbase public key>


Expected pruning mode

If you encounter the following errors:

Error: Service(Client(Msg("State database error: Expected pruning
mode: constrained")))

It means you previously started the node without mining flag. By default, the node would execute under pruning mode which currently cannot be used for mining.

To fix it, run the following command and then restart your mining node.

kulupu purge-chain

Unable to mine

If you see any of the "unable to mine" errors in the log, please ensure that you have started the mining node with approriate --author flag and have imported your mining key.

  • "Unable to mine: pre-digest not set" means the --author flag is missing from the command-line.

  • "Unable to mine: fetch pair from author failed" means the mining key has not been imported. Please refer to "import or generate a mining key" section to get the mining key to the node.

Custom base path

If you use a custom base path through the --base-path or -d flag, when importing the mining key, the flag should also be present for the keystore import to obtain the correct path.

Node killed

If you see your node about to generate the RandomX cache and getting killed, it is due to the machine not having enough memory. You can get the mining routine running by setting up swap memory (Linux) or virtual memory (Windows). However, do note that if you do this, the mining will be done with degraded performance.

Warnings that can be ignored

If you encountered the following warnings, they are normal and can be ignored:

  • "Ran out of free WASM instances" means it is generating new WASM instances.

  • "This peer ID uses a legacy, deprecated representation" can be ignored. You can also attempt to fix it by completely remove the data store and restart the node.