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MetaMask talks to Lumera through the Ethereum JSON-RPC endpoint that every EVM enabled node serves. This page gives you the network values, a manual setup walkthrough, account import for migrated keys, and fixes for the most common connection errors. The EVM is live on testnet (lumera-testnet-2) only. Mainnet gains the EVM with its upgrade, so point MetaMask at testnet for now. See the EVM upgrade page for what changes.

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Use the EVM endpoint, not the Cosmos endpoints

The MetaMask RPC URL is not the same as the Keplr RPC URL. Keplr is a Cosmos wallet and talks to the LCD and CometBFT endpoints. MetaMask talks only to the EVM JSON-RPC endpoint, a separate service on a different port and URL. Pasting a Cosmos URL into MetaMask is the most common reason a connection fails with “could not fetch chain ID”.
Only the EVM JSON-RPC row belongs in a MetaMask network configuration. The Cosmos endpoints never answer eth_chainId, so MetaMask cannot use them.

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Network values

Use these values to add Lumera testnet to MetaMask. The EVM chain ID 76857769 is the same on every Lumera network. JSON-RPC responses return it as hex 0x494c1a9. The mainnet EVM endpoint is https://evm-rpc.lumera.io and starts answering once mainnet completes its EVM upgrade. If you run a node yourself, MetaMask on the same machine can use http://localhost:8545. Verify an endpoint before adding it.
The response must include the chain ID in hex.

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Add the network manually

1

Open the network selector

Open MetaMask and click the network name in the top left corner.
2

Add a custom network

Choose “Add a custom network”. Older versions call it “Add network manually”.
3

Enter the network values

Fill in the fields from the table above and save the network.
4

Switch to the new network

Select the network in the selector. MetaMask fetches the chain ID from the RPC URL to confirm it.
If MetaMask says it cannot fetch the chain ID, the RPC URL is not an EVM JSON-RPC endpoint or the endpoint is unreachable from your browser. See troubleshooting below.
The Lumera Portal can configure the network for you. When you connect MetaMask on the testnet Portal, it checks eth_chainId, switches with wallet_switchEthereumChain, and only shows the “Add network” popup (wallet_addEthereumChain) if MetaMask does not know the chain yet. If no MetaMask popup appears, click the MetaMask icon in your browser toolbar. Chrome sometimes suppresses it.

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One account, two addresses

Lumera uses Ethereum style keys (eth_secp256k1, coin type 60). The same account has two representations. Both point to the same funds and the same state. Apps like the Lumera Portal show both forms after you connect.
MetaMask may label your native balance as ETH on custom networks. The amount is still your LUME balance. The EVM side reports the 18 decimal denom alume, where 1 ulume equals 10^12 alume, so the values line up exactly.

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Import a migrated account

Accounts created before a network’s EVM upgrade use coin type 118 and must be migrated on chain before they work in MetaMask. The migration produces a matching 0x... and lumera1... pair on a coin type 60 key. See the EVM upgrade page for the migration itself, then import the key.
1

Open the account list

In MetaMask, open the account selector and choose “Add wallet”.
2

Import the key

Choose “Import a wallet” for a 12, 18, or 24 word Secret Recovery Phrase, or “Import an account” for a single private key. Enter the secret for the migrated key.
3

Rename the account

Open the account menu, choose “Rename”, and give the account a clear label so you can find it later.
Only import a Secret Recovery Phrase or private key you own and control. Never paste a seed phrase into a website. Enter it only in the MetaMask extension’s own import screen.

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Troubleshooting

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MetaMask cannot fetch the chain ID

Test the RPC URL directly.
The response must include "result":"0x494c1a9". If it returns Method not found, the URL points at CometBFT RPC instead of EVM JSON-RPC. Watch for these common mistakes.
  • An LCD URL such as https://lumera-testnet-api.polkachu.com is Cosmos REST, not EVM JSON-RPC.
  • A CometBFT URL such as https://lumera-testnet-rpc.polkachu.com is consensus RPC, not EVM JSON-RPC.
  • http://localhost:8545 only works when MetaMask runs on the same machine as the node.

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Requests fail in the browser but curl works

The endpoint likely has a DNS, TLS, or CORS problem. MetaMask rejects invalid HTTPS certificates, and browsers enforce CORS preflight checks that curl skips. If you operate the endpoint, check those three layers from a machine outside the server.

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Running your own public endpoint

Exposing a node’s EVM JSON-RPC over HTTPS needs a reverse proxy with TLS, CORS headers, and rate limiting. That setup is an operator task and lives in the MetaMask configuration guide on GitHub, including nginx examples for hostname based and path based proxies plus WebSocket support.

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Next steps

Deploy with Remix

Deploy your first Solidity contract with Remix and MetaMask.

Get testnet LUME

Fund your account with testnet tokens for gas.

EVM upgrade and migration

Migrate a legacy account to the EVM key format.