Typically this error is from configuration issues. I've always seen it with second message as well as additional information in the Report Server Services log. From what you are saying, you are getting neither of those so that is very unusual. The second message and the reporting services logs would be the other steps.
It could be whatever has been done or changed for SSL. If you don't have a certificate on the SSRS server, you can't setup SSL on the report server. If IIS is on the same computer, that can also have an effect on how SSL connections are processed.

I would double check the changes you made to the configuration file as well as the settings in Reporting Services Configuration Manager.
I'm not sure which log file you checked either - if you made changes to log HTTP errors, those errors are logged to a different log file from the Report server services log (ReportServerServiceLog_<timestamp>.log)
The file name for the HTTP errors log is in the ReportingServicesService.exe.config file
There are two different log files if you enabled HTTP logging and they both have different information. If nothing else, set the Report Server Services trace log to verbose.

Sue