From fc45daeb1e3b197e3f07c8cba2e391c585678002 Mon Sep 17 00:00:00 2001
From: Alonso Rodriguez <ARR552@users.noreply.github.com>
Date: Wed, 19 Apr 2023 19:51:27 +0200
Subject: [PATCH] fix wrong state root when prevlastbatch & lastbatch are empty
 + restart (#2028)

---
 jsonrpc/endpoints_eth_test.go |  4 ++--
 sequencer/dbmanager.go        | 22 ++++++++++++++++++----
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/jsonrpc/endpoints_eth_test.go b/jsonrpc/endpoints_eth_test.go
index cfcaab2419..ed688b9032 100644
--- a/jsonrpc/endpoints_eth_test.go
+++ b/jsonrpc/endpoints_eth_test.go
@@ -626,7 +626,7 @@ func TestEstimateGas(t *testing.T) {
 					Once()
 				m.State.
 					On("EstimateGas", txMatchBy, *txArgs.From, nilUint64, m.DbTx).
-					Return(*testCase.expectedResult, nil).
+					Return(*testCase.expectedResult, nil, nil).
 					Once()
 			},
 		},
@@ -667,7 +667,7 @@ func TestEstimateGas(t *testing.T) {
 
 				m.State.
 					On("EstimateGas", txMatchBy, common.HexToAddress(c.DefaultSenderAddress), nilUint64, m.DbTx).
-					Return(*testCase.expectedResult, nil).
+					Return(*testCase.expectedResult, nil, nil).
 					Once()
 			},
 		},
diff --git a/sequencer/dbmanager.go b/sequencer/dbmanager.go
index 7f3acfd246..31ec924e92 100644
--- a/sequencer/dbmanager.go
+++ b/sequencer/dbmanager.go
@@ -260,12 +260,26 @@ func (d *dbManager) GetWIPBatch(ctx context.Context) (*WipBatch, error) {
 	if err != nil {
 		return nil, err
 	}
-
 	lastBatch.Transactions = lastBatchTxs
 
-	lastStateRoot, err := d.state.GetLastStateRoot(ctx, dbTx)
-	if err != nil {
-		return nil, err
+	var prevLastBatchTxs []types.Transaction
+	if previousLastBatch != nil {
+		prevLastBatchTxs, _, err = state.DecodeTxs(previousLastBatch.BatchL2Data)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	var lastStateRoot common.Hash
+	// If the last two batches have no txs, the stateRoot can not be retrieved from the l2block because there is no tx.
+	// In this case, the stateRoot must be gotten from the previousLastBatch
+	if len(lastBatchTxs) == 0 && previousLastBatch != nil && len(prevLastBatchTxs) == 0 {
+		lastStateRoot = previousLastBatch.StateRoot
+	} else {
+		lastStateRoot, err = d.state.GetLastStateRoot(ctx, dbTx)
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	wipBatch := &WipBatch{