Across Bridge works when the connected wallet is on the chain holding the spendable token and gas; retrying a quote from the wrong chain cannot repair it. That source-network choice decides every result downstream.
Mia is moving 250 USDC from Ethereum to Base. Her wallet shows the same 0x address on both networks, so she assumes the address proves she is ready. It does not. Before she sends anything, three separate balances must make sense: 250 USDC on the source chain, enough source-chain ETH for approval and sending, and a destination-chain balance that will appear only after delivery.
| What Mia sees | What it actually checks | What a retry changes |
|---|---|---|
| 250 USDC in the wallet | Which network holds it | Nothing |
| Same 0x address on Base | Destination account identity | Nothing |
| ETH for gas | Whether Ethereum can process approval and deposit | Only if gas was added |
When “no route available” appears, put the wallet on the chain that owns Mia’s USDC
Failure: Mia selects Ethereum as the route’s source, but the form says no route is available or shows a zero balance.
Cause: Her wallet is still connected to Base, where that address has no spendable USDC. A bridge can use the address on both EVM networks, but it cannot spend Ethereum USDC while the wallet is signing from Base.
Fix: Switch the wallet itself to Ethereum, refresh the page, then choose Ethereum as source and Base as destination. Now open the Across Bridge transfer screen; on the other side is the live route form, where the source, destination, token, amount, fee, and delivery estimate must all describe the same transfer. Do not approve until its source balance matches Mia’s 250 USDC.
When the balance is there but “insufficient funds” remains, separate USDC from Ethereum gas
Failure: The form recognizes 250 USDC, but Mia cannot approve or submit the transfer.
Cause: USDC pays for the amount bridged; it does not pay Ethereum’s transaction fee. The approval and the bridge deposit are separate on-chain actions. If Mia has 250 USDC and 0 ETH, the amount is real but the transaction cannot start.
Fix: Leave a practical ETH buffer on Ethereum before reducing the USDC amount. Read the wallet’s displayed gas estimate immediately before signing, because network conditions change. Then approve the exact USDC amount and submit the route once. A second approval is not a substitute for missing gas.
When the wallet asks for an approval you did not expect, verify the token and allowance before signing
Failure: Mia expected one transfer but sees an approval request first.
Cause: USDC is an ERC-20 token. The bridge contract must receive permission to move the chosen amount before it can deposit it. This is normal only when the token, source chain, receiving contract, and allowance shown by the wallet match the route Mia just reviewed.
Fix: Compare four items before approving: Ethereum as the active network, USDC as the asset, the amount or allowance, and the wallet’s destination contract details. If the wallet changed networks, the token is different, or the request no longer matches the quote, reject it and restart from the source-chain check.
When the transaction is confirmed but Base still looks empty, follow the route rather than sending again
Failure: Mia sees Ethereum confirmation, opens Base, and finds no usable USDC immediately.
Cause: Source-chain confirmation is only the first milestone. The route still needs to be relayed and filled or settled on Base. Switching networks too early can also hide the arrival because the wallet has not refreshed its Base token list.
Fix: Keep the source transaction hash, wait for the route’s stated delivery status to complete, then switch to Base and refresh the USDC balance. Add the correct Base USDC token only if the wallet fails to display a balance that the completed route reports. Never send the 250 USDC again merely because the first transaction is confirmed.
Answer what remains before Mia tries again
Does the same address on Ethereum and Base mean the funds are shared?
No. It identifies the same wallet account, but each network keeps a separate balance and transaction history.
Does Mia need ETH on Base before receiving?
Usually no; receiving the bridged token does not itself require her to submit a Base transaction. She will need Base ETH later to move or swap it.
Should Mia cancel because delivery takes longer than expected?
Not while the source transaction and route are still pending or processing. Check the route status first; only act on a clearly failed transaction, not on an impatient refresh.