diff --git a/executor/substate_provider.go b/executor/substate_provider.go
index 7a235a39..adf9f1a1 100644
--- a/executor/substate_provider.go
+++ b/executor/substate_provider.go
@@ -19,6 +19,8 @@ package executor
 //go:generate mockgen -source substate_provider.go -destination substate_provider_mocks.go -package executor
 
 import (
+	"errors"
+
 	"github.com/0xsoniclabs/aida/txcontext"
 	substatecontext "github.com/0xsoniclabs/aida/txcontext/substate"
 	"github.com/0xsoniclabs/aida/utils"
@@ -53,21 +55,21 @@ type substateProvider struct {
 
 func (s substateProvider) Run(from int, to int, consumer Consumer[txcontext.TxContext]) error {
 	iter := s.db.NewSubstateIterator(from, s.numParallelDecoders)
+	release := func(err error) error {
+		iter.Release()
+		return errors.Join(err, iter.Error())
+	}
+
 	for iter.Next() {
 		tx := iter.Value()
 		if tx.Block >= uint64(to) {
-			// TODO bug not release
-			return nil
+			return release(nil)
 		}
 		if err := consumer(TransactionInfo[txcontext.TxContext]{int(tx.Block), tx.Transaction, substatecontext.NewTxContext(tx)}); err != nil {
-			// TODO bug not release
-			return err
+			return release(err)
 		}
 	}
-	// this cannot be used in defer because Release() has a WaitGroup.Wait() call
-	// so if called after iter.Error() there is a change the error does not get distributed.
-	iter.Release()
-	return iter.Error()
+	return release(nil)
 }
 
 func (s substateProvider) Close() {
diff --git a/executor/substate_provider_test.go b/executor/substate_provider_test.go
index adddae78..0a638b3e 100644
--- a/executor/substate_provider_test.go
+++ b/executor/substate_provider_test.go
@@ -257,6 +257,79 @@ func TestSubstateProvider_Run(t *testing.T) {
 	assert.NoError(t, err)
 }
 
+func TestSubstateProvider_Run_ReleasesIteratorOnUpperBound(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	mockDb := db.NewMockSubstateDB(ctrl)
+	mockIter := db.NewMockIIterator[*substate.Substate](ctrl)
+	mockDb.EXPECT().NewSubstateIterator(0, 0).Return(mockIter)
+	mockIter.EXPECT().Next().Return(true)
+	mockIter.EXPECT().Value().Return(&substate.Substate{
+		Block: 1,
+	})
+	mockIter.EXPECT().Release().Return()
+	mockIter.EXPECT().Error().Return(nil)
+
+	provider := &substateProvider{
+		db: mockDb,
+	}
+	err := provider.Run(0, 1, func(info TransactionInfo[txcontext.TxContext]) error {
+		t.Fatal("consumer must not be called for transactions outside the requested range")
+		return nil
+	})
+	assert.NoError(t, err)
+}
+
+func TestSubstateProvider_Run_ReleasesIteratorOnConsumerError(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	mockDb := db.NewMockSubstateDB(ctrl)
+	mockIter := db.NewMockIIterator[*substate.Substate](ctrl)
+	mockDb.EXPECT().NewSubstateIterator(0, 0).Return(mockIter)
+	mockIter.EXPECT().Next().Return(true)
+	mockIter.EXPECT().Value().Return(&substate.Substate{
+		Block: 0,
+	})
+	mockIter.EXPECT().Release().Return()
+	mockIter.EXPECT().Error().Return(nil)
+
+	consumerErr := errors.New("consumer failed")
+	provider := &substateProvider{
+		db: mockDb,
+	}
+	err := provider.Run(0, 1, func(info TransactionInfo[txcontext.TxContext]) error {
+		return consumerErr
+	})
+	assert.ErrorIs(t, err, consumerErr)
+}
+
+func TestSubstateProvider_Run_ReturnsIteratorErrorAfterRelease(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	mockDb := db.NewMockSubstateDB(ctrl)
+	mockIter := db.NewMockIIterator[*substate.Substate](ctrl)
+	mockDb.EXPECT().NewSubstateIterator(0, 0).Return(mockIter)
+	mockIter.EXPECT().Next().Return(true)
+	mockIter.EXPECT().Value().Return(&substate.Substate{
+		Block: 1,
+	})
+	mockIter.EXPECT().Release().Return()
+	iterErr := errors.New("iterator failed")
+	mockIter.EXPECT().Error().Return(iterErr)
+
+	provider := &substateProvider{
+		db: mockDb,
+	}
+	err := provider.Run(0, 1, func(info TransactionInfo[txcontext.TxContext]) error {
+		t.Fatal("consumer must not be called for transactions outside the requested range")
+		return nil
+	})
+	assert.ErrorIs(t, err, iterErr)
+}
+
 func TestSubstateProvider_Close(t *testing.T) {
 	ctrl := gomock.NewController(t)
 	defer ctrl.Finish()