Patch #67 on stage_file_proxy 8.x-1.1 worked for me. However, The application...

Patch #67 on stage_file_proxy 8.x-1.1 worked for me. However, The application that I am working on serves the private files from the overridden path(not system/files). Hence I had to save the patch locally and make below changes:

• The private files directory in my application is configured via settings.php in $settings['file_private_path'], So I updated the FetchManager.php file's code $file_dir = $this->fetchInfoService->getLocalSchemePath($fetchInfo->getScheme()); to $file_dir = \Drupal\Core\Site\Settings::get('file_private_path');. This ensures that stage_file_proxy saves the private files at the location from which they are read/served.
• The functions getUrlBasePath() & getFetchInfo() of SfpPrivateStream.php class has hardcoded the paths system/files & system/files/styles respectively. However, In my case, the files were being served from different paths and hence I updated it to suit my need.

The above changes made the patch #67 work for me.