1. What versions are you using?

oracledb: 1.0.3
python: 3.10.5
database: 19.10.0.0.0

2. Is it an error or a hang or a crash?

crash

4. What error(s) or behavior you are seeing?

DPY-2019: python-oracledb thick mode cannot be used because a thin mode connection has already been created

5. Does your application call init_oracle_client()?

Yes. Im trying to use thin mode first and switch to thick when the database is incompatible

6. Include a runnable Python script that shows the problem.

try:
  connection = oracledb.connect(params=params)
except oracledb.NotSupportedError as err:
  print( err.args[0].message ) # DPY-3015: password verifier type 0x939 is not supported by python-oracledb in thin mode
  oracledb.init_oracle_client()  # Try fallback in thick mode
  connection = oracledb.connect(params=params)