diff --git a/canopen/sdo/client.py b/canopen/sdo/client.py
index 6d92588e..2a82ed12 100644
--- a/canopen/sdo/client.py
+++ b/canopen/sdo/client.py
@@ -669,6 +669,8 @@ def __init__(self, sdo_client, index, subindex=0, size=None, request_crc_support
         self._blksize, = struct.unpack_from("B", response, 4)
         logger.debug("Server requested a block size of %d", self._blksize)
         self.crc_supported = bool(res_command & CRC_SUPPORTED)
+        # Run this last, used later to determine if initialization was successful
+        self._initialized = True
 
     def write(self, b):
         """
@@ -784,6 +786,9 @@ def close(self):
         if self.closed:
             return
         super(BlockDownloadStream, self).close()
+        if not getattr(self, "_initialized", False):
+            # Don't do finalization if initialization was not successful
+            return
         if not self._done:
             logger.error("Block transfer was not finished")
         command = REQUEST_BLOCK_DOWNLOAD | END_BLOCK_TRANSFER
diff --git a/canopen/sdo/server.py b/canopen/sdo/server.py
index c6a4c27c..2947afd0 100644
--- a/canopen/sdo/server.py
+++ b/canopen/sdo/server.py
@@ -120,6 +120,10 @@ def request_aborted(self, data):
 
     def block_download(self, data):
         # We currently don't support BLOCK DOWNLOAD
+        # Unpack the index and subindex in order to send appropriate abort
+        command, index, subindex = SDO_STRUCT.unpack_from(data)
+        self._index = index
+        self._subindex = subindex
         logger.error("Block download is not supported")
         self.abort(0x05040001)