Web3 New Added 9 October 2026

Solidity: CompilerError: Stack too deep. Try compiling with --via-ir

The EVM can only reach the top 16 slots of its stack, and the function the error points at needs more than that for its locals, parameters and return values at once. The legacy code generator cannot move values to memory to make room, so it gives up. The IR pipeline can, which is why the compiler suggests it, at the cost of slower compiles and sometimes different gas costs.

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.

Quick fix

# Hardhat (hardhat.config.js)
solidity: {
  version: "0.8.28",
  settings: { viaIR: true, optimizer: { enabled: true, runs: 200 } }
}

# Foundry (foundry.toml)
[profile.default]
via_ir = true
optimizer = true

# solc directly
solc --via-ir --optimize contracts/Vault.sol

# Or cut stack use in that function: group locals into a memory struct,
# split it into internal functions, or scope temporaries in { } blocks

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.

Simulate before sending: eth_call against the same block returns the revert reason string that a submitted transaction hides.
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.
For nonce errors, query the account's pending nonce (eth_getTransactionCount with the pending tag) rather than tracking it locally.
To replace a stuck transaction, resend with the same nonce and a materially higher gas price: most nodes require at least a 10% increase.
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.soliditylang.org docs.soliditylang.org

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