ORA-26213
The flag to distinguish beginning or resuming a flex transaction is missing or incorrect.
Cause
The argument that distinguishes beginning a new flex transaction and resuming an existing transaction is not correctly set.
Action
If flex transaction is started on client, specify either OCI_TRANS_NEW or OCI_TRANS_RESUME in the flags. If the transaction is started on server via PL/SQL function, specify either TRANSACTION_NEW or TRANSACTION_RESUME as flag.