JSON-RPC

Error reference

Codes that come from Arc, and codes that come from us. The second group exists to turn a silent Arc failure into something your client can catch.

Code	Source	Meaning	Fix
-32001	arc	Pending transaction access denied by Arc	Use newHeads or logs; txpool_* for pool inspection on our endpoints
-32014	arc	requested data not available, returned for the pending block tag by Circle's public endpoint	Query latest; on Arc latest is already final
-32004	arc	arc_getCertificate: no certificate for that height	Check the height exists; the response height is decimal
-32005	arc	arc_getCertificate: the consensus layer did not answer	Retry; the node proxies this call to its consensus endpoint
-32010	arc	Every configured transaction relay is unreachable	Retry the send after a short backoff
-32600	arc	Batch larger than 100 requests	Split the batch into chunks of 100 or fewer
-32000	arc	intrinsic gas too high on eth_createAccessList	Pass an explicit gas value in the call object
-32603	arc	Unimplemented method on the Reth execution client	eth_coinbase and eth_mining have no meaning on a BFT chain
-32020	arcrpc	below_base_fee_floor	Raise maxFeePerGas to at least 20 Gwei, or set belowFloorPolicy to autobump
-32021	arcrpc	pending_tag_unsupported	An explicit error in place of the silent null Arc returns
-32022	arcrpc	decimal_mismatch_guard	An 18 decimal value was passed where 6 was expected, or the reverse
401	arcrpc	Key missing, revoked or out of scope	Check the key, its method scope and its IP allowlist
429	arcrpc	Rate limit	Back off using retry-after, or raise plan RPS

The quiet failures

Three Arc behaviours produce no error at all on a standard endpoint: a transaction under the base fee floor vanishes, eth_getBlockByNumber("pending") returns null, and eth_getTransactionBySenderAndNonce returns null. We convert the first to -32020 and the second to -32021 so they surface in your error handling rather than in a reconciliation report.

Response headers

Every response carries x-arcrpc-units, x-arcrpc-region and x-arcrpc-node-build. The last one is the same string arc_getVersion returns, so a support ticket can name the build without a round trip.