Hi All, 

Just to share a solution for error code "The report server cannot decrypt the symmetric key used to access sensitive or encrypted data in a report server database" when reinstalling Information Server.

PCS 7 V9.0 SP 3 UC05 , SIMATIC Information Server 2014 SP3 Update 6. 

1. I failed to configure HTTPS for Information server, while troubleshooting, i reconfigure it back to http just to check whether the system is healthy. 

 2. Go to C:\Program Files (x86) \Siemens\Information Server\Configuration Manager\ConfigurationManager.exe

3. Execute the reconfiguration but stuck at reporting service. 

4. Went to troubleshoot via the log file %programdata%siemens\automation\logfiles\configurationmanager.log. 

5. Found the error code "The report server cannot decrypt the symmetric key used to access sensitive or encrypted data in a report server database"

6. Then google search the error code and found this link https://spgeeks.devoworx.com/ssrs-error-the-report-server-cannot-decrypt-the-symmetric-key-used-to-access-sensitive-or-encrypted-data-in-a-report-server-database/ 

7. went to sql server 2014 reporting service , login , select encryption keys, delete encrypted content

8. rerun configuration manager, issue resolved. 

Hope it is helpful for thos who see this thread in the future.