Unable to open PDF attachment in browser window from JIRA Issue View

Summary

After Upgrading to JIRA 6.4.x , it is no possible to open PDF attachment in a new window

PDF attachment can be viewed in a new window without downloading the attachment in JIRA version 6.3.12

Environment

(Optional - If Applicable)

• Google Chrome

Steps to Reproduce

1. Create Issue > Attach .pdf file
2. View Create Issue > Right-click and open the .pdf file in a new window

Expected Results

1. Should be able to view the .pdf file in a new window without downloading the file as it behaves in JIRA 6.3.12
   
   

Actual Results

1. the .pdf file refuse to be opened in the new window. It automatically downloads the .pdf file.
   
   

Notes

(Optional - If Necessary)

Workaround

• None