How to Switch MetaMask from Ethereum Mainnet to Arbitrum Safely

11 October 2026

Switching MetaMask from Ethereum mainnet to Arbitrum safely requires selecting the correct Arbitrum network from the network selector, ensuring you have the correct RPC details, and verifying you are on the right chain before sending any transactions. The process is straightforward if you follow the steps below, but mistakes - like connecting to a fake Arbitrum network or forgetting to switch back - can cost you funds.

Why you need to switch networks

MetaMask defaults to Ethereum mainnet. To interact with Arbitrum - a layer-2 scaling solution - you must add and select its network. Arbitrum uses its own chain ID and RPC endpoints, separate from Ethereum. If you send Ethereum mainnet transactions while on Arbitrum, or vice versa, your transaction may fail or tokens could be lost.

Step-by-Step: Add and Switch to Arbitrum Safely

1. Open the Network Selector

In MetaMask, click the network dropdown at the top of the extension window. It usually shows "Ethereum Mainnet" by default.

2. Check if Arbitrum Is Already Listed

Scroll through the list. If "Arbitrum One" appears, you can select it directly. If not, you need to add it manually.

3. Add the Arbitrum Network Manually

Click "Add Network" at the bottom of the dropdown. MetaMask may offer a list of popular networks. If Arbitrum One appears in that list, select it and confirm. If not, click "Add Network Manually" and enter these details exactly:

• Network Name: Arbitrum One
• RPC URL: https://arb1.arbitrum.io/rpc
• Chain ID: 42161
• Symbol: ETH
• Block Explorer URL: https://arbiscan.io

Double-check every character. A typo in the RPC URL or chain ID can connect you to a malicious network. You can verify the correct details on the official Arbitrum documentation site.

4. Save and Switch

Click "Save." MetaMask will prompt you to switch to the new network. Confirm. The network selector should now show "Arbitrum One."

5. Verify You Are on the Correct Network

Before doing anything else, check that the network badge (the icon next to the network name) and the chain ID match. A quick way: open a block explorer like Arbiscan in a separate tab and compare the network ID shown there with what MetaMask displays in the "Settings > Networks" menu.

Common problems and fixes

"Network Not Found" or "Failed to Add Network"

• Cause: Incorrect RPC URL or chain ID.
• Fix: Delete the network entry from MetaMask (Settings > Networks > Arbitrum One > Remove) and re-add it using the official details above. Avoid copying RPC URLs from random websites.

Balance shows zero after switching

• Cause: You only have ETH on Ethereum mainnet, not on Arbitrum.
• Fix: You need to bridge ETH from Ethereum mainnet to Arbitrum using an official bridge. Do not attempt to send ETH directly to your Arbitrum address from mainnet - it will not appear. Use a trusted bridge service like the official Arbitrum Bridge.

Transaction stuck or pending

• Cause: Arbitrum uses a different gas mechanism than mainnet. Transactions can take longer if the network is congested.
• Fix: You can speed up a pending transaction by clicking the pending transaction in MetaMask and selecting "Speed Up." Alternatively, cancel it and resend with a higher gas limit. Arbitrum generally has lower fees than mainnet, but they still fluctuate.

"Insufficient Funds for Gas" When You Have ETH

• Cause: You are likely still on Ethereum mainnet, not Arbitrum. Or you have ETH on mainnet but not on Arbitrum.
• Fix: Confirm which network is selected. If on Arbitrum, you need ETH there, which requires bridging. If on mainnet, you need ETH there.

Connected to the Wrong Arbitrum Network (e.g., Arbitrum Nova vs. Arbitrum One)

• Cause: There are multiple Arbitrum networks (One, Nova, Goerli testnet). Each has a different chain ID and purpose.
• Fix: Ensure you are on "Arbitrum One" (chain ID 42161) for the main layer-2. Arbitrum Nova (chain ID 42170) is for gaming and social apps. Testnets have no real value. Check the chain ID before transacting.

Avoiding Scams

Fake Arbitrum networks exist. Scammers create networks with similar names (e.g., "Arbitrum Official") and malicious RPC endpoints. To avoid them:

• Only add networks from the official Arbitrum documentation or trusted sources like the MetaMask popular list.
• Never paste RPC details from a social media post, email, or unverified website.
• If a dApp asks you to add a network automatically, verify the chain ID and RPC URL in MetaMask before approving. The pop-up shows the details - read them.

Switching back to ethereum mainnet

To return to mainnet, simply open the network selector and choose "Ethereum Mainnet." Your tokens and transaction history remain intact on each network. You cannot see mainnet balances while on Arbitrum, but they are still there.

Summary

The most common mistake is not checking the chain ID. Always confirm you are on chain ID 42161 before bridging or trading. If something feels off, stop and verify the network details against official sources.

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