diff --git a/pybtc/connector.py b/pybtc/connector.py
index e0bcd7b..aa0c43d 100644
--- a/pybtc/connector.py
+++ b/pybtc/connector.py
@@ -414,8 +414,9 @@ class Connector:
                 raise Exception("duplicated block")
         if "previousblockhash" not in block :
             return
-        self.log.critical(str(self.block_cache.get_last()))
-        self.log.critical(str(block["previousblockhash"]))
+        lb = self.block_cache.get_last()
+        if lb is None and not self.last_block_height:
+            return
         if self.block_cache.get_last() != block["previousblockhash"]:
             if self.block_cache.get(block["previousblockhash"]) is None and self.last_block_height:
                 self.log.critical("Connector error! Node out of sync "