diff --git a/proposer/proposer.go b/proposer/proposer.go
index f58371911..e32bfe8b8 100644
--- a/proposer/proposer.go
+++ b/proposer/proposer.go
@@ -320,7 +320,11 @@ func (p *Proposer) ProposeOp(ctx context.Context) error {
 
 	for i, err := range p.ProposeTxLists(ctx, txListsBytes) {
 		if err != nil {
-			log.Error("Failed to send TaikoL1.proposeBlock transaction", "index", i, "error", err)
+			log.Error(
+				"Failed to send TaikoL1.proposeBlock transaction",
+				"index", i,
+				"error", encoding.TryParsingCustomError(err),
+			)
 			continue
 		}
 
diff --git a/proposer/transaction_builder/blob.go b/proposer/transaction_builder/blob.go
index 601f77428..db831b06d 100644
--- a/proposer/transaction_builder/blob.go
+++ b/proposer/transaction_builder/blob.go
@@ -129,7 +129,7 @@ func (b *BlobTransactionBuilder) Build(
 	// Send the transaction to the L1 node.
 	data, err := encoding.TaikoL1ABI.Pack("proposeBlock", encodedParams, []byte{})
 	if err != nil {
-		return nil, encoding.TryParsingCustomError(err)
+		return nil, err
 	}
 
 	return &txmgr.TxCandidate{
diff --git a/proposer/transaction_builder/calldata.go b/proposer/transaction_builder/calldata.go
index 469ab1bd7..5af830040 100644
--- a/proposer/transaction_builder/calldata.go
+++ b/proposer/transaction_builder/calldata.go
@@ -109,7 +109,7 @@ func (b *CalldataTransactionBuilder) Build(
 	// Send the transaction to the L1 node.
 	data, err := encoding.TaikoL1ABI.Pack("proposeBlock", encodedParams, txListBytes)
 	if err != nil {
-		return nil, encoding.TryParsingCustomError(err)
+		return nil, err
 	}
 
 	return &txmgr.TxCandidate{