While opening categories,occuring PAGE NOT FOUND error

Steps to repro->
1.Click on Template management
2.Select Template
3.Click on Notes
4.Click on add new Categories
5.Add File
7.Click on that File without uploading

Actual result :-Occuring error for first time when file gets open as shown in attachment
strong text
Expected result :- It should not give error

CC-Aniruddha DevHrishikesh DeshpandeRakesh Roy