Version mismatch,
Such as: Python connection times wrong 64 - bit Oracle Oracle database Client library always be the loaded:
At this point need to check the python, cx_Oracle, and Oracle client side version are consistent;
The Oracle client version if inconsistent with the other two versions, the
(1) to the website to download the client version of the corresponding system, do not need to install, directly to the client package into corresponding PLSQL under the root directory, if the original has been installed 32-bit client, can need not uninstall, directly to the 64 - bit client unpack the package directly

(2) then configure access path, i.e., tnsnames. Ora file (direct copy other people's network file directly into the oracle client list below).

(3) the configuration environment variables, pay attention to the configuration to the client only root directory,
C: \ ProgramFileshjt \ Oracle \ product \ instantclient_19_8