Navakanth
In our case the issue first appeared when we tried to run SUM from a NFS mount. After moving to a local folder we resolved the issue deleting the SUM folder and decompressing it again. I think that in the movement we lost some permissions and that caused the problem.
After resolving that, we faced another issue in which the first screen appears but never loads the interface. That was resolved killing all java threads launched by SUM and restarting all the procedure.
Best regards,