Tx Doctor / EVM error library / ERC-20 allowance too low
EVM error: ERC-20 allowance too low
The router or contract was not approved to spend that many of your tokens, so the transferFrom call reverted.
Why it happens
- No approve() was sent before the swap or deposit.
- The allowance was already spent by an earlier transaction.
- The approval went to a different router address than the one being called (v2 vs v3 vs universal router).
- USDT-style tokens require resetting the allowance to zero before setting a new one.
How to fix it
- Approve the exact contract that is being called — copy the spender address from the failing transaction.
- Approve the exact amount, or use Permit2 / permit signatures where the dApp supports them.
- For USDT, approve 0 first, then approve the new amount.
What it looks like in the wallet or explorer
ERC20: insufficient allowance
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