The report server has encountered a configuration error. See the report server log files for more information. (rsServerConfigurationError)
When you try to open the SQL Server Reporting Services Report Manager, you might get the error saying "The report server has encountered a configuration error. See the report server log files for more information. (rsServerConfigurationError)".
When you go and check for the Error Logs you might find an error saying "Access to the path 'C:\Program Files\Microsoft SQL Server\MSSQL.4\Reporting Services\ReportServer\RSReportServer.config' is denied." Note the path may vary as per your installation, but error would be similar.
This might be either after first time installation or sometime later installation as well. There might be various reasons for this. Some of the reasons are:
1. During Installation, you have just opted to Install the SSRS but not opted to be configured. If so, what happens is, the database will be created and the SSRS will not be configured.
2. For some reason, the database might have dropped or moved to different server, but this is not re-configured in Reporting services configuration manager.
3. The service account which is running SSRS service might not have access to read the configuration file.
To resolve this,
When you open Reporting Services Configuration Manager, Go to databases and See whether the Default database is configured. If its Blank the Go Ahead and Create the New Database for Reporting Service or If you have already existing database then go ahead and provide the Datbase information.
After this Go to MSSQLSERVER Installation Directory and Under ReportingServices Folder give the Permission to the Service Account in which Reporting Service Server is running.