Attachments not upload in SugarCRM

Dear Team,

I have upgrade SugarCRM version 9.0.1 to 11.0.6 . 
When i try to upload any attachments in any Cases using SugarCRM screen no reflected any error and showing file uploaded but i am try to view or download the same file facing issue attached screenshot.
  
I have facing file upload and download error from CRM screen.

Thanks & Regards,
Suraj Kumar