oracle19c支持低版本plsql
1、登录服务器
${ORALCE_HOME}/network/admin/sqlnet.ora增加
cd ${ORALCE_HOME}
vi ./network/admin/sqlnet.ora
sqlnet.ora：如没有文件，新增
SQLNET.ALLOWED_LOGON_VERSION_SERVER=8
SQLNET.ALLOWED_LOGON_VERSION_CLIENT=8
2、重启监听
sqlplus / as sysdba
shutdown immediate;
startup;
3、修改用户密码
alter user [userName] identified by [userPwd];