EVM / Solidity Error 0xe450d38c: ERC20InsufficientBalance

Identify: does your log match?

Error: execution reverted (unknown custom error) (action="estimateGas", data="0xe450d38c00000000000000000000000070997970c51812dc3a010c7d01b50e0d17dc79c800000000000000000000000000000000000000000000000d8d726b7177a8000000000000000000000000000000000000000000000000003635c9adc5dea00000", reason=null, transaction={ "data": "0xa9059cbb...", "from": "0x70997970C51812dc3A010C7d01b50e0d17dc79C8", "to": "0x5FbDB2315678afecb367f032d93F642f64180aa3" }, invocation=null, revert=null, code=CALL_EXCEPTION, version=6.13.4)

1. High

   Amount not scaled by decimals

   Passing 1000 * 10**18 to a 6-decimal token (USDC) asks for 10^12 times too much. Always read decimals().

2. Medium

   Wrong sender in transferFrom

   transferFrom checks the from address's balance, not the caller's. The vault or user you pull from is empty.

3. Low

   Fee-on-transfer or rebasing token

   The received amount was less than expected, so a follow-up transfer of the full amount exceeds the actual balance.

Fix

await token.transfer(to, amount); // "unknown custom error"

import { Contract, Interface, parseUnits } from 'ethers';

const iface = new Interface([
  'error ERC20InsufficientBalance(address sender, uint256 balance, uint256 needed)',
]);
const decimals = await token.decimals();
const amount = parseUnits('250', decimals);
try {
  await token.transfer.staticCall(to, amount);
} catch (e: any) {
  const parsed = iface.parseError(e.data);
  if (parsed?.name === 'ERC20InsufficientBalance') console.log(parsed.args.balance, parsed.args.needed);
}

Verify: reproduce it on purpose

$ cast decode-error 0xe450d38c00000000000000000000000070997970c51812dc3a010c7d01b50e0d17dc79c800000000000000000000000000000000000000000000000d8d726b7177a8000000000000000000000000000000000000000000000000003635c9adc5dea00000 --sig "ERC20InsufficientBalance(address,uint256,uint256)"

Prevent

• Add OZ IERC20Errors to your frontend ABI.
• Never hardcode 18 decimals.
• Show balance vs needed in the UI before signing.