ERC-20 Error 0xe450d38c: ERC20InsufficientBalance Custom Error
Error 0xe450d38c is the OpenZeppelin Contracts v5 custom error ERC20InsufficientBalance(address sender, uint256 balance, uint256 needed). It replaces legacy string reverts ("ERC20: transfer amount exceeds balance") to save contract deployment and execution gas fees. This error occurs when an account attempts to transfer or spend more ERC-20 tokens than its current balance allows. Check token decimal conversions (e.g. 6 decimals for USDC vs 18 for DAI) to avoid scaling errors.
# Root Cause & Technical Architecture
OpenZeppelin Contracts v5 migrated from string revert reasons to Solidity custom errors. Selector `0xe450d38c` represents `bytes4(keccak256("ERC20InsufficientBalance(address,uint256,uint256)"))`. Inside `_update()`, the contract checks: `if (senderBalance < value) revert ERC20InsufficientBalance(sender, senderBalance, value)`. This occurs frequently when frontend code passes raw 18-decimal numbers to 6-decimal tokens like USDC/USDT, multiplying required balance by $10^{12}$.
# 4-Step Actionable Diagnostic Protocol
Step-by-Step ResolutionCheck Token Decimals Configuration
Query token.decimals() on-chain. Formatting 100 USDC with parseEther ("100000000000000000000") instead of parseUnits(100, 6) causes immediate reverts.
Decode Exact Revert Data Values
Use cast 4byte-decode 0xe450d38c... to inspect the three decoded fields: the sender address, the actual current balance, and the needed amount.
Account for Fee-on-Transfer Deductions
If the token applies a transfer tax or deflationary burn, subsequent transfer calls within the same transaction may receive fewer tokens than anticipated.
Verify Wrapped Token Unwrapping
Confirm you are holding the ERC-20 token (e.g. WETH), not the native cryptocurrency (ETH), when executing smart contract deposit calls.
# Diagnostic Verification Code / Command
solidity// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/ERC20.sol)
error ERC20InsufficientBalance(address sender, uint256 balance, uint256 needed);
// 4-byte selector: 0xe450d38c
function _update(address from, address to, uint256 value) internal virtual {
if (from != address(0)) {
uint256 fromBalance = _balances[from];
if (fromBalance < value) {
// Reverts with selector 0xe450d38c + (from, fromBalance, value)
revert ERC20InsufficientBalance(from, fromBalance, value);
}
}
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# Related Diagnostic Codes in EVM & JSON-RPC
Related Hex StatusesJSON-RPC Error -32000: Insufficient Funds for Gas * Price + Value
Fix JSON-RPC error -32000 insufficient funds for gas * price + value. Resolve native token balance shortages, fee estimation surges, and gas caps.
JSON-RPC Error -32000: Replacement Transaction Underpriced Fix
Fix JSON-RPC error -32000 replacement transaction underpriced. Apply mandatory 10%+ maxPriorityFeePerGas bump on same nonce to replace stuck mempool txs.
JSON-RPC Error -32000: Nonce Too Low Stale Wallet State Fix
Fix JSON-RPC error -32000 nonce too low. Troubleshoot stale local wallet nonce caches, pending mempool transactions, and reset account state.
# Frequently Asked Questions
FAQ SchemaWhy did OpenZeppelin switch to custom errors like 0xe450d38c?
Custom errors save bytecode deployment size and reduce runtime gas consumption by ~50 gas per revert compared to storing and returning long error strings.
How do I decode 0xe450d38c in Foundry?
Run "cast 4byte-decode <raw_revert_hex>" in your terminal. Foundry will automatically display the sender, current balance, and required amount.
Can I get this error if I have enough balance but no gas?
No. Having insufficient native gas tokens causes RPC error -32000. 0xe450d38c strictly indicates an insufficient ERC-20 token balance.