JSON-RPC error codes - Autheo documentation

JSON-RPC errors are returned as objects with a code and message field inside the error key of the response.

{
  "jsonrpc": "2.0",
  "id": 1,
  "error": {
    "code": -32601,
    "message": "Method not found"
  }
}

Standard JSON-RPC error codes

Code	Name	Description
`-32700`	Parse error	Invalid JSON was received
`-32600`	Invalid request	The JSON is not a valid request object
`-32601`	Method not found	The method does not exist or is unsupported
`-32602`	Invalid params	Invalid method parameters
`-32603`	Internal error	Internal JSON-RPC server error
`-32000` to `-32099`	Server error	Implementation-defined server errors

Ethereum execution errors

Code	Message	Description
`-32000`	`execution reverted`	Contract execution reverted — check the `data` field for the revert reason
`-32000`	`insufficient funds for gas * price + value`	Sender balance too low
`-32000`	`nonce too low`	Transaction nonce is lower than the account’s current nonce
`-32000`	`nonce too high`	Transaction nonce is too far ahead of the current nonce
`-32000`	`gas limit reached`	Block gas limit exceeded
`-32000`	`already known`	Transaction already in mempool

Decoding revert reasons

When a transaction reverts, the data field may contain an ABI-encoded revert reason:

import { ethers } from "ethers";

try {
  await contract.myFunction(args);
} catch (err) {
  if (err.data) {
    // Try to decode as a standard Error(string) revert
    try {
      const decoded = ethers.toUtf8String("0x" + err.data.slice(138));
      console.error("Revert reason:", decoded);
    } catch {
      console.error("Raw revert data:", err.data);
    }
  }
}

Common causes and fixes

Error	Likely cause	Fix
`-32601 Method not found`	Method not supported by this node	Check supported methods
`-32000 execution reverted`	Contract `require()` or `revert()` triggered	Simulate with `eth_call` first to get revert reason
`-32000 insufficient funds`	Low balance	Fund the sender account
`-32000 nonce too low`	Stale nonce in client	Refresh nonce with `eth_getTransactionCount`