SQLSTATE[HY000] [1045] Access denied for user 'root'@'' (using password: NO) in Live Server

I have created 2 instances in google cloud.One instance is working fine but on other instance it shows SQLSTATE[HY000] [1045] Access denied for user 'root'@'ip' (using password: NO). I have checked all the details in .env file they are correct. How to solve this issue in live server ??

via Chebli Mohamed