Caused by: java.lang.RuntimeException: Unable to obtain credentials to communicate with the Cloud SQL API
This error comes if "application_default_credentials.json" file is not there in "C:\Users\<USER_NAME>\AppData\Roaming\gcloud\"
To populate this JSON file, run below command in cmd prompt;
command : gcloud auth application-default login
So this will create "application_default_credentials.json" file in the above directory. Now, you can restart your spring boot application.