diff --git a/cmd/bot/run.go b/cmd/bot/run.go
index 1c4e225..7a1eb5f 100644
--- a/cmd/bot/run.go
+++ b/cmd/bot/run.go
@@ -103,25 +103,29 @@ func ProcessUnprovenBotDelegatedWithdrawals(ctx context.Context, log log.Logger,
 	for _, unproven := range unprovens {
 		err := processor.ProveWithdrawalTransaction(ctx, &unproven)
 		if err != nil {
-			if strings.Contains(err.Error(), "OptimismPortal: withdrawal hash has already been proven") {
+			errStr := err.Error()
+			if strings.Contains(errStr, "OptimismPortal: withdrawal hash has already been proven") {
 				// The withdrawal has already proven, mark it
 				result := db.Model(&unproven).Update("proven", true)
 				if result.Error != nil {
 					log.Error("failed to update proven l2_contract_events", "error", result.Error)
 				}
-			} else if strings.Contains(err.Error(), "L2OutputOracle: cannot get output for a block that has not been proposed") {
+			} else if strings.Contains(errStr, "L2OutputOracle: cannot get output for a block that has not been proposed") {
 				// Since the unproven withdrawals are sorted by the on-chain order, we can break here because we know
 				// that the subsequent of the withdrawals are not ready to be proven yet.
 				return
-			} else if strings.Contains(err.Error(), "execution reverted") {
+			} else if strings.Contains(errStr, "execution reverted") {
 				// Proven transaction reverted, mark it with the failure reason
-				result := db.Model(&unproven).Update("failure_reason", err.Error())
+				if len(errStr) >= 255 {
+					errStr = errStr[len(errStr)-255:]
+				}
+				result := db.Model(&unproven).Update("failure_reason", errStr)
 				if result.Error != nil {
 					log.Error("failed to update failure reason of l2_contract_events", "error", result.Error)
 				}
 			} else {
 				// non-revert error, stop processing the subsequent withdrawals
-				log.Error("ProveWithdrawalTransaction", "non-revert error", err.Error())
+				log.Error("ProveWithdrawalTransaction", "non-revert error", errStr)
 				return
 			}
 		}