Link Plsql error ora-01033:oracle initialization or shutdown in process

Connect to the database via Plsql, and the ora-01033:oracle initialization or shutdown in progress prompt message pops up.
I found a dependent solution on the Internet, as follows

The client Oracle server enters the PL/SQL developer times ora-01033:oracle Initializationg or shutdown in progress error message that the application system cannot connect to the Oracle service. Solve the problem by remote guidance. The process is as follows:

1. Enter cmd and execute set Oracle_sid=fbms to ensure the correct SID is connected.
2, running Sqlplus "/as sysdba"

2. SQL>shutdown immediate 停止服务
4. SQL>startup 启动服务，观察启动时有无数据文件加载报错，并记住出错数据文件标号
6. ```
8. SQL>shutdown immediate 再次停止服务
10. SQL>startup mount
12. SQL> recover datafile 2 依次恢复出错的数据文件
14. SQL>shutdown immediate 再次停止服务
16. SQL>startup 启动服务，此次正常。

3, into the PL/SQL developer check, no longer prompt error.

Link Plsql error ora-01033:oracle initialization or shutdown in process