diff --git a/premix/debug.nim b/premix/debug.nim
index c4a7d9333..2e8f0cc63 100644
--- a/premix/debug.nim
+++ b/premix/debug.nim
@@ -20,14 +20,18 @@ proc executeBlock(blockEnv: JsonNode, memoryDB: TrieDatabaseRef, blockNumber: Ui
     body   = chainDB.getBlockBody(header.blockHash)
 
   let
+    transaction = memoryDB.beginTransaction()
     vmState = newBaseVMState(parent, chainDB)
     validationResult = processBlock(chainDB, parent, header, body, vmState)
 
-  if validationResult != ValidationResult.OK:
+  if validationResult != ValidationResult.OK:    
     error "block validation error", validationResult
   else:
     info "block validation success", validationResult, blockNumber
 
+  # success or not dispose it
+  transaction.dispose()
+  
   dumpDebuggingMetaData(chainDB, header, body, vmState, false)
   let
     fileName = "debug" & $blockNumber & ".json"