Reporting Services Registry access error

We have an existing setup of SQL 2014 & SP 2013 Foundation server which works fine without any issues. Then, we have been installed the following components into SQL Server

• Reporting Services – SharePoint


• Reporting Services Add-in for SharePoint

Then, I provisioned a new SQL Reporting Services Service Application in SharePoint.When attempting to Manage the Service Application and click on ‘System Settings’ in Central admin of SharePoint and getting below error.

The report server cannot decrypt the symmetric key that is used to access sensitive or encrypted data in a report server database. You must either restore a backup key or delete all encrypted content. ---> Microsoft.ReportingServices.Library.ReportServerDisabledException. The report server cannot decrypt the symmetric key that is used to access sensitive or encrypted data in a report server database. You must either restore a backup key or delete all encrypted content. --->System.Security.SecurityException.Requested registry account is not allowed.

I understand from my investigation, an above said error should thrown only if I'm changing the user of reporting services. But in my case, I Just installed Reporting services and trying to do the configuration. Not sure why I'm getting such registry access error.