From 732f5468d33ae184dfa518fb75b9da87efeee940 Mon Sep 17 00:00:00 2001
From: Michael Ruminer <michael.ruminer+github@gmail.com>
Date: Sat, 9 Dec 2017 17:47:13 -0500
Subject: [PATCH] eth: make tracing API errors more user friendly (#15589)

---
 eth/api.go | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/eth/api.go b/eth/api.go
index a907c3649..c748f75de 100644
--- a/eth/api.go
+++ b/eth/api.go
@@ -452,7 +452,12 @@ func (api *PrivateDebugAPI) traceBlock(block *types.Block, logConfig *vm.LogConf
 	}
 	statedb, err := blockchain.StateAt(blockchain.GetBlock(block.ParentHash(), block.NumberU64()-1).Root())
 	if err != nil {
-		return false, structLogger.StructLogs(), err
+		switch err.(type) {
+		case *trie.MissingNodeError:
+			return false, structLogger.StructLogs(), fmt.Errorf("required historical state unavailable")
+		default:
+			return false, structLogger.StructLogs(), err
+		}
 	}
 
 	receipts, _, usedGas, err := processor.Process(block, statedb, config)
@@ -518,7 +523,12 @@ func (api *PrivateDebugAPI) TraceTransaction(ctx context.Context, txHash common.
 	}
 	msg, context, statedb, err := api.computeTxEnv(blockHash, int(txIndex))
 	if err != nil {
-		return nil, err
+		switch err.(type) {
+		case *trie.MissingNodeError:
+			return nil, fmt.Errorf("required historical state unavailable")
+		default:
+			return nil, err
+		}
 	}
 
 	// Run the transaction with tracing enabled.