How to Connect Remix to a Private Ethereum Chain and Fix Common Errors

Connecting Remix to a Private Ethereum Chain

After writing a Solidity contract, you can deploy it to a local private chain using Remix by following these steps:

Start a Geth node or another wallet that exposes a JSON‑RPC endpoint.

Open Remix and click the Run tab.

Select Web3 Provider as the environment.

When prompted with “Are you sure you want to connect to an ethereum node?”, click OK .

Enter the node address, typically http://localhost:8545, and confirm.

If the connection succeeds, Remix will display the accounts and balances from the private chain.

Click Deploy to publish the smart contract.

During this process you may encounter the following error:

Not possible to connect to the Web3 provider. Make sure the provider is running and a connection is open (via IPC or RPC).

Solutions

Solution 1: Use HTTP URL

Some users report that changing the Remix URL from https://remix.ethereum.org to http://remix.ethereum.org can bypass the error, although browsers often auto‑redirect back to HTTPS, so this method may not always work.

Solution 2: Add the --rpccorsdomain Flag

On Chrome (other browsers may not work), you can start Geth with an explicit CORS domain flag to allow browser‑based RPC requests. Even though recent Geth versions accept connections without this flag, certain versions or browser configurations require it.

The flag is defined as:

--rpccorsdomain value   Comma‑separated list of domains from which to accept cross‑origin requests (browser enforced)

Setting the value to * permits any origin: --rpccorsdomain "*" Example full startup command on macOS:

/Users/zzs/my/book/geth1.8/geth \
  --datadir /Users/zzs/my/book/geth1.8/geth/data \
  --rpc \
  --rpccorsdomain "*" \
  --rpcapi "db,eth,net,web3,miner,personal" \
  --ipcpath /Users/zzs/my/book/geth1.8/geth/data/geth.ipc \
  --dev >info.log 2>&1 &