diff --git a/packages/taiko-client/internal/metrics/metrics.go b/packages/taiko-client/internal/metrics/metrics.go
index 99e13a18480..4ac2d510674 100644
--- a/packages/taiko-client/internal/metrics/metrics.go
+++ b/packages/taiko-client/internal/metrics/metrics.go
@@ -34,6 +34,7 @@ var (
 	ProposerEstimatedCostBlob      = factory.NewGauge(prometheus.GaugeOpts{Name: "proposer_estimated_cost_blob"})
 	ProposerProposeByCalldata      = factory.NewCounter(prometheus.CounterOpts{Name: "proposer_propose_by_calldata"})
 	ProposerProposeByBlob          = factory.NewCounter(prometheus.CounterOpts{Name: "proposer_propose_by_blob"})
+	ProposerCostEstimationError    = factory.NewGauge(prometheus.GaugeOpts{Name: "proposer_cost_estimation_error"})
 
 	// Prover
 	ProverLatestVerifiedIDGauge      = factory.NewGauge(prometheus.GaugeOpts{Name: "prover_latestVerified_id"})
diff --git a/packages/taiko-client/proposer/transaction_builder/fallback.go b/packages/taiko-client/proposer/transaction_builder/fallback.go
index 903966672fe..3f1c988b460 100644
--- a/packages/taiko-client/proposer/transaction_builder/fallback.go
+++ b/packages/taiko-client/proposer/transaction_builder/fallback.go
@@ -122,6 +122,7 @@ func (b *TxBuilderWithFallback) BuildOntake(
 
 	if err = g.Wait(); err != nil {
 		log.Error("Failed to estimate transactions cost, will build a type-3 transaction", "error", err)
+		metrics.ProposerCostEstimationError.Inc()
 		// If there is an error, just build a blob transaction.
 		return b.blobTransactionBuilder.BuildOntake(ctx, txListBytesArray)
 	}