1."Don't download list file" Patch server not available

2."Failed to download file" = you lost connection with the patch server

3."Rohan Online already running" = Delete Rohan folder and reinstall game

4."Failed to load Gem.cfg-0" = Bad download or bad install. Need to reinstall

How to fix :
1-Remove rohan and delete all folder.Then reinstall.
2-(When 1 doesn't work) Go to your Rohan folder and rename rohanclient.exe to fairyclient.exe. Next run loader.exe let it update
Try the above and see if it works.