From 1cf71d17bdb4822a027ef6754ea2a870b78c3c78 Mon Sep 17 00:00:00 2001
From: Rod Vagg <rod@vagg.org>
Date: Thu, 8 Jan 2026 22:43:52 +1100
Subject: [PATCH 1/2] fix(eth): use error code 3 for EExecutionReverted

BREAKING: RPC error codes changed - EActorNotFound (from 3 to 11),
EExecutionReverted (from 11 to 3). Mismatched client/server versions will
deserialize these errors as the wrong Go type, breaking errors.Is/As
checks.

Swap EExecutionReverted and EActorNotFound positions so that
EExecutionReverted gets code 3, the de facto Ethereum standard for
execution reverted errors. This enables proper error decoding by
Ethereum tooling like viem, ethers.js, and other RPC clients.

Error code 3 was introduced in geth v1.9.15 and is now expected by
most Ethereum ecosystem tooling for automatic ABI decoding of revert
reasons from the error data field.

Ref: https://github.com/ethereum/go-ethereum/pull/21083
Ref: https://github.com/ethereum/go-ethereum/pull/31456
Ref: https://github.com/ethereum/go-ethereum/issues/21886
Ref: https://github.com/wevm/viem/blob/6c11882938673e939830027f47ed73e907f2b90e/src/utils/errors/getContractError.ts
Ref: https://www.quicknode.com/docs/ethereum/error-references
Ref: https://docs.metamask.io/services/reference/ethereum/json-rpc-methods/eth_call/
---
 api/api_errors.go   |  4 ++--
 itests/fevm_test.go | 28 ++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/api/api_errors.go b/api/api_errors.go
index 3d4854261fd..480518ff099 100644
--- a/api/api_errors.go
+++ b/api/api_errors.go
@@ -19,7 +19,7 @@ var invalidExecutionRevertedMsg = xerrors.New("invalid execution reverted error"
 
 const (
 	EOutOfGas = iota + jsonrpc.FirstUserCode
-	EActorNotFound
+	EExecutionReverted
 	EF3Disabled
 	EF3ParticipationTicketInvalid
 	EF3ParticipationTicketExpired
@@ -27,7 +27,7 @@ const (
 	EF3ParticipationTooManyInstances
 	EF3ParticipationTicketStartBeforeExisting
 	EF3NotReady
-	EExecutionReverted
+	EActorNotFound
 	ENullRound
 	EPaymentChannelDisabled
 )
diff --git a/itests/fevm_test.go b/itests/fevm_test.go
index 53daa49c815..8611f245b10 100644
--- a/itests/fevm_test.go
+++ b/itests/fevm_test.go
@@ -1066,6 +1066,34 @@ func TestFEVMErrorParsing(t *testing.T) {
 			})
 		})
 	}
+
+	// Verify that the raw JSON-RPC error code is 3, per Ethereum standard for execution reverted.
+	// See: https://github.com/ethereum/go-ethereum/pull/21083 (geth v1.9.15)
+	t.Run("RawErrorCode3", func(t *testing.T) {
+		entryPoint := kit.CalcFuncSignature("failRevertReason()")
+
+		request := fmt.Sprintf(`{
+			"jsonrpc": "2.0",
+			"id": 1,
+			"method": "eth_call",
+			"params": [{"to": "%s", "data": "0x%x"}, "latest"]
+		}`, contractAddrEth.String(), entryPoint)
+
+		statusCode, responseBody := client.DoRawRPCRequest(t, 1, request)
+		require.Equal(t, 200, statusCode)
+
+		var rpcResponse struct {
+			Error struct {
+				Code    int    `json:"code"`
+				Message string `json:"message"`
+				Data    string `json:"data"`
+			} `json:"error"`
+		}
+		require.NoError(t, json.Unmarshal(responseBody, &rpcResponse))
+		require.Equal(t, 3, rpcResponse.Error.Code,
+			"execution reverted error code must be 3 for Ethereum RPC compatibility (EIP-1474 de facto standard)")
+		require.NotEmpty(t, rpcResponse.Error.Data, "error response should include revert data")
+	})
 }
 
 // TestEthGetBlockReceipts tests retrieving block receipts after invoking a contract

From ae5fb597eedc5e83fb69176a9ba277b364dd1477 Mon Sep 17 00:00:00 2001
From: Rod Vagg <rod@vagg.org>
Date: Thu, 8 Jan 2026 22:53:18 +1100
Subject: [PATCH 2/2] fixup! fix(eth): use error code 3 for EExecutionReverted

---
 CHANGELOG.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 925fd418730..729c37d1b45 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,8 @@
 ## 👌 Improvements
 - docs: fix outdated link in documentation ([#13436](https://github.com/filecoin-project/lotus/pull/13436))
 - docs: fix dead link in documentation ([#13437](https://github.com/filecoin-project/lotus/pull/13437))
+- fix(eth): use error code 3 for EExecutionReverted for Ethereum RPC tooling compatibility ([filecoin-project/lotus#13467](https://github.com/filecoin-project/lotus/pull/13467))
+  - BREAKING: RPC error codes changed - EActorNotFound (3→11), EExecutionReverted (11→3). Mismatched client/server versions will deserialize these errors as the wrong Go type, breaking errors.Is/As checks.
 
 # Node v1.34.3 / 2025-12-03