About "http://localhost:9700/.hc"

After I finished survey solution‘s installation on AWS,I got unhealthy when I open “http://localhost:9700/.hc”. Anyone know the reason?

when logged in as admin user you can see detailed diagnostics on the http://localhost:9700/Administration/Diagnostics/ page

It says “Application cannot connect to database using provided connection string”.

Do you know why this happen?

Yes I do - exactly what it says in the error message, whatever connection information was provided during the setup is incorrect.

You can find the database connection string in site\application.production.ini file.
It has a format Server=127.0.0.1; Port=5432;User Id=user;Password=password
you need to check if you didn’t make any typos when entering password. If you installed postgresql on the same machine, the address would be 127.0.0.1 but if you instead used amazon’s RDS service, then make sure the proper address is set and the security groups are setup as in the documentation.