ethers v6: Cannot read properties of undefined (reading 'Web3Provider')

Quick fix

Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.

# Which major version is installed?
npm ls ethers

# v5 to v6 renames
#  new ethers.providers.Web3Provider(window.ethereum) -> new ethers.BrowserProvider(window.ethereum)
#  new ethers.providers.JsonRpcProvider(url)          -> new ethers.JsonRpcProvider(url)
#  ethers.utils.parseEther("1.0")                     -> ethers.parseEther("1.0")
#  ethers.utils.formatUnits(x, 6)                     -> ethers.formatUnits(x, 6)
#  ethers.constants.AddressZero                       -> ethers.ZeroAddress
#  BigNumber.from(x), a.add(b)                        -> BigInt(x), a + b
#  provider.getSigner()                               -> await provider.getSigner()

# Or pin v5 until the migration is done
npm install ethers@5

How to diagnose Web3 errors

Web3 errors are unusually terse because the EVM reports failure without explanation by default. execution reverted means a require or revert triggered. The reason string is present in the return data but most libraries discard it. Nonce errors reflect the strict sequential ordering of transactions per account, so a stuck transaction blocks every one behind it.

If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.

1. Simulate before sending: eth_call against the same block returns the revert reason string that a submitted transaction hides.
2. Use a transaction tracer (Tenderly, Foundry's cast run, or a node's debug_traceTransaction) to see the exact opcode and contract where execution reverted.
3. For nonce errors, query the account's pending nonce (eth_getTransactionCount with the pending tag) rather than tracking it locally.
4. To replace a stuck transaction, resend with the same nonce and a materially higher gas price: most nodes require at least a 10% increase.
5. Check the chain ID matches the network you intend. Signing for the wrong chain produces confusing rejection messages.

Tools worth reaching for

• cast (Foundry)
• eth_call simulation
• Tenderly / block explorer tracer
• debug_traceTransaction

Authoritative references

Primary documentation for this error, worth reading before applying any fix in production.

📖 docs.ethers.org

Related Web3 errors

• MetaMask Tx Signature: User denied transaction signature (4001)Code 4001 is the EIP-1193 "user rejected" error: the person clicked Reject or closed the…
• Solidity: CompilerError: Stack too deep. Try compiling with --via-irThe EVM can only reach the top 16 slots of its stack, and the function the error points at…
• Web3: already known / ALREADY_EXISTS when sending a transactionThe node already holds a transaction with this exact hash in its pool, so the resend is…
• Web3: cannot estimate gas; transaction may fail or may require manual gas limitThe node ran the transaction against current state and it reverted, so no gas figure could be…
• Web3: could not detect network (event="noNetwork", code=NETWORK_ERROR)ethers asks the endpoint for its chain id before it will do anything else, and that call…
• Web3: execution revertedThe smart contract reverted. Solidity custom errors or revert strings often explain the exact…
• Web3: gas required exceeds allowance (0)The node simulated the transaction and found the sender cannot cover it, so the allowance it…
• Web3: insufficient funds for gas * price + valueThe wallet lacks enough native token to pay transaction value plus gas. This is separate from…

See all 17 Web3 errors →

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Something missing or wrong?

This entry is maintained by hand. If the fix is out of date, incomplete, or you have a better one, email a correction and it will be reviewed.