How to resolve oracle db refuse to listener error

I was facing this issue mutiple times. I am not sure why. It keeps telling me that my db is in starting progress. Will update the image later,

What I did everytime I am facing this issue is

1. Open Sqlplus
2. Login as sysdba using command "/as SYSDBA"
3. Change permission for your pluggadable database

"alter pluggable database pdborcl open read write;"

pdborcl = my pluggadable database.