diff --git a/asammdf/blocks/mdf_v4.py b/asammdf/blocks/mdf_v4.py
index a84ee11b6..31b3878b0 100644
--- a/asammdf/blocks/mdf_v4.py
+++ b/asammdf/blocks/mdf_v4.py
@@ -536,7 +536,6 @@ def _read(self, mapped=False):
                 continue
 
             if group.raw_can:
-
                 try:
                     _sig = self.get("CAN_DataFrame", group=i, ignore_invalidation_bits=True)
                 except MdfException:
@@ -1543,9 +1542,6 @@ def _append_structure_composition(
         inval_bits,
         inval_cntr,
     ):
-
-        print(signal, signal.samples.dtype)
-
         si_map = self._si_map
 
         fields = []
diff --git a/asammdf/blocks/utils.py b/asammdf/blocks/utils.py
index 961fb5060..f68a9e400 100644
--- a/asammdf/blocks/utils.py
+++ b/asammdf/blocks/utils.py
@@ -1517,33 +1517,37 @@ def pandas_query_compatible(name):
 
 
 def load_can_database(file, contents=None):
+
     file = Path(file)
 
     dbc = None
 
-    if file.exists() and file.suffix.lower() in ('.dbc', '.arxml'):
-        import_type = file.suffix.lower().strip('.')
-        loads = dbc_load if import_type == 'dbc' else arxml_load
-        if contents is None:
+    if file.suffix.lower() in ('.dbc', '.arxml'):
+        if contents is None and file.exists():
             contents = file.read_bytes()
-        contents = BytesIO(contents)
-        try:
-            dbc = loads(
-                contents,
-                import_type=import_type,
-                key="db",
-            )
-        except UnicodeDecodeError:
-            encoding = detect(contents)["encoding"]
-            contents = contents.decode(
-                encoding
-            )
-            dbc = loads(
-                contents,
-                importType=import_type,
-                import_type=import_type,
-                key="db",
-                encoding=encoding,
-            )
+
+        if contents:
+            import_type = file.suffix.lower().strip('.')
+            loads = dbc_load if import_type == 'dbc' else arxml_load
+
+            contents = BytesIO(contents)
+            try:
+                dbc = loads(
+                    contents,
+                    import_type=import_type,
+                    key="db",
+                )
+            except UnicodeDecodeError:
+                encoding = detect(contents)["encoding"]
+                contents = contents.decode(
+                    encoding
+                )
+                dbc = loads(
+                    contents,
+                    importType=import_type,
+                    import_type=import_type,
+                    key="db",
+                    encoding=encoding,
+                )
 
     return dbc
diff --git a/asammdf/mdf.py b/asammdf/mdf.py
index 2a1ca9a14..da3835a56 100644
--- a/asammdf/mdf.py
+++ b/asammdf/mdf.py
@@ -3687,6 +3687,9 @@ def extract_can_logging(self, dbc_files, version=None, ignore_invalid_signals=Fa
                 if not group.CAN_logging:
                     continue
 
+                if not 'CAN_DataFrame' in [ch.name for ch in group.channels]:
+                    continue
+
                 parents, dtypes = self._prepare_record(group)
                 data = self._load_data(group)
 
@@ -3736,7 +3739,7 @@ def extract_can_logging(self, dbc_files, version=None, ignore_invalid_signals=Fa
                         bus_msg_ids = msg_ids.samples[idx]
                         bus_data_bytes = data_bytes[idx]
 
-                        unique_ids = np.unique(bus_msg_ids)
+                        unique_ids = np.unique(bus_msg_ids).astype('<u8')
 
                         for msg_id in unique_ids:
                             message = messages.get(msg_id, None)