Why a Token Approval Fails in a Self-Custody Wallet

A failed token approval usually means the token contract did not record permission for the requested spender to use tokens from your wallet. The wallet holds the signing key and submits the transaction, but the token contract controls the allowance. A decentralized application asks for permission; the wallet shows the request; the token contract updates the allowance only if the transaction executes successfully.

For a typical ERC-20 token, the application names a spender contract and requests an amount. Your wallet signs an approve transaction and pays the network fee. Validators include it in a block, and the token contract checks and records the allowance. A later swap or deposit calls another contract, which tries to move tokens within that approved limit. A blackhole swap walkthrough follows that wallet-to-trade sequence in more detail.

Why does a token approval fail?

First, find out whether the transaction reached the chain. If the wallet rejected the request or the transaction never left the wallet, no approval was executed. If a transaction appears on a block explorer as reverted or failed, the contract call ran but did not complete; the allowance generally remains as it was. The network fee can still be charged for an on-chain failure.

Common causes include an insufficient native token balance to pay the fee, a stale or incorrect network selection, or a contract rejecting the requested call. Some older tokens also reject changing an allowance directly from one nonzero amount to another. For those tokens, the allowance may need to be set to zero first, then set to the new amount in a separate transaction. A wallet’s simulation or provider can also report an error before anything is broadcast.

How can I diagnose a failed approval?

Start with the transaction status, then check the allowance for the correct token, wallet address and network. A successful approval on one chain does not grant permission on another. Compare the spender address shown in the request with the contract address used by the application. If the transaction succeeded but the next action failed, the second call may be asking a different spender to use the tokens, or more tokens than the recorded allowance permits.

• Confirm the wallet and application are on the intended network.
• Check whether the approval is pending, failed or confirmed in the wallet or a block explorer.
• Verify the token contract and spender address, and read the current allowance if your wallet or explorer provides it.
• Check that the wallet has enough of the network’s native token to cover another transaction fee.

If the transaction is pending, avoid repeatedly submitting the same request: a pending transaction can block later transactions from that wallet until it confirms, is replaced or is cancelled. Follow the wallet’s own process for handling it. If it failed on-chain, inspect the error details before trying again.

What should I do before retrying?

Retry only after you know what failed. Correct the network, fund the wallet for fees, or use the token’s required allowance sequence if the error points to one. Review the spender and amount in the new wallet prompt. A smaller allowance limits how much that spender can draw, though it may mean approving again for a later transaction. An approval is a permission stored by the token contract; disconnecting the website from your wallet does not remove it. If an old permission is no longer needed, check the allowance and revoke it with a transaction on the same network.