Fixed bug that would cause an internal error to be raised when

attempting to close a connection that has been forcibly closed by the
database.

Author: anthony-tuininga

doc/src/release_notes.rst

@@ -20,6 +20,8 @@ Thin Mode Changes
 #)  Fixed bug in handling invisible columns with object type names containing
     ``%ROWTYPE``
     (`issue 325 <https://github.com/oracle/python-oracledb/issues/325>`__).
+#)  Fixed bug that would cause an internal error to be raised when attempting
+    to close a connection that has been forcibly closed by the database.
 #)  Internal change: further efforts to tighten code looking for the end of a
     database request made to Oracle Database 23c.
 

src/oracledb/impl/thin/protocol.pyx

@@ -157,7 +157,8 @@ cdef class Protocol(BaseProtocol):
         with self._request_lock:
 
             # if a read failed on the socket earlier, clear the socket
-            if self._read_buf._transport is None:
+            if self._read_buf._transport is None \
+                    or self._read_buf._transport._transport is None:
                 self._transport = None
 
             # if the session was marked as needing to be closed, force it