diff --git a/proposer/proposer.go b/proposer/proposer.go
index 62161cd9c..dd38e1846 100644
--- a/proposer/proposer.go
+++ b/proposer/proposer.go
@@ -5,6 +5,7 @@ import (
 	"context"
 	"fmt"
 	"math/rand"
+	"strings"
 	"sync"
 	"time"
 
@@ -363,7 +364,29 @@ func (p *Proposer) ProposeTxLists(ctx context.Context, txListsBytes [][]byte) []
 		txCandidates[i] = *candidate
 	}
 
-	return p.txSender.SendAndWaitDetailed("proposeBlock", txCandidates...)
+	// Send the transactions to the TaikoL1 contract, and if any of them fails, try
+	// to parse the custom error.
+	errors := p.txSender.SendAndWaitDetailed("proposeBlock", txCandidates...)
+	for i, err := range errors {
+		if err == nil {
+			continue
+		}
+
+		// If a transaction is reverted on chain, the error string returned by txSender will like this:
+		// fmt.Errorf("%w purpose: %v hash: %v", ErrTransactionReverted, txPurpose, rcpt.Receipt.TxHash)
+		// Then we try parsing the custom error for more details in log.
+		if strings.Contains("purpose: ", err.Error()) && strings.Contains("hash: ", err.Error()) {
+			txHash := strings.Split(err.Error(), "hash: ")[1]
+			receipt, err := p.rpc.L1.TransactionReceipt(ctx, common.HexToHash(txHash))
+			if err != nil {
+				log.Error("Failed to fetch receipt", "txHash", txHash, "error", err)
+				continue
+			}
+			errors[i] = encoding.TryParsingCustomErrorFromReceipt(ctx, p.rpc.L1, p.proposerAddress, receipt)
+		}
+	}
+
+	return errors
 }
 
 // updateProposingTicker updates the internal proposing timer.