If your bridge says the wallet network does not match, compare the wallet’s chain ID with the bridge’s selected source network; that number decides where the source transaction runs. A chain ID is a network’s numeric identifier. Ethereum mainnet uses ID 1, while Polygon PoS uses ID 137.
The chain ID tells your wallet which network it is using
A network is a separate blockchain with its own transaction history and balances. Your wallet can use the same account address on Ethereum and Polygon PoS, but it checks a chain ID to know which network to read or send transactions on.
MetaMask may show a network name, such as “Polygon,” but the name is only a label. The ID is the key check: Ethereum’s ID is 1, and Polygon PoS’s ID is 137. A custom network can have a misleading name, so check its ID against a trusted source.
A bridge transfer has a source network, where your tokens start, and a destination network, where they should arrive. For a transfer from Ethereum to Polygon, Ethereum is the source. The wallet must be ready to sign the first transaction on Ethereum, even if the bridge has Polygon selected as the destination.
A mismatch means the wallet and bridge disagree about the source
The bridge uses its selected networks to prepare a transfer, while the wallet uses its current chain ID to sign the transaction. If those do not line up, the bridge may ask you to switch networks or refuse to continue. This check helps prevent a transaction from being sent to the wrong chain.
For example, imagine the bridge is set to send 20 USDC from Ethereum to Polygon, but MetaMask is on Polygon. The bridge expects a transaction on chain ID 1; the wallet reports 137. Switch MetaMask to Ethereum before signing. The destination remains Polygon, and the bridge handles delivery there.
The Polygon Bridge is one example of a service for moving supported tokens between Ethereum and Polygon. Its selected source network must match the wallet’s chain when you sign the source transaction. Seeing Polygon as the destination does not mean the wallet should already be on Polygon for an Ethereum deposit.
The bridge moves tokens through two separate chain actions
A bridge is a service that coordinates a token transfer between blockchains. For an Ethereum-to-Polygon PoS transfer, the source transaction sends tokens to a bridge contract, a program that holds or manages tokens. The bridge then makes the corresponding token available on Polygon.
For a Polygon-to-Ethereum withdrawal, the flow reverses: the Polygon-side tokens are burned, meaning removed from circulation, and the bridge later releases the corresponding tokens on Ethereum. A checkpoint is a record of Polygon activity submitted to Ethereum so the release can be verified. The wallet may need to switch to the destination network to see or claim tokens there.
Each chain action costs gas, the network fee for processing a transaction. You pay the source chain’s fee in its native token: typically ETH on Ethereum or POL on Polygon PoS. A first-time token transfer can also require an approval, which is permission for the bridge contract to use that token; that approval is a separate transaction and has its own gas cost.
Check the source before signing
Before approving or signing, compare the bridge’s source network with the wallet’s selected network and chain ID. For an Ethereum deposit, confirm ID 1; for a Polygon PoS withdrawal, confirm ID 137. Then check the token and amount in the wallet’s transaction details.
If the IDs match but the bridge still reports a mismatch, reconnecting the wallet or refreshing the page can update stale network information. Do not approve a transaction whose network or token details you cannot verify. The decision rule is simple: sign only when the wallet’s chain ID matches the bridge’s selected source network.