I get a blank VisualForce page with Fetch Endpoint in Jira 7.6 and above when clickjacking protection is enabled
Summary
In JIRA v7.6 and above, even after performing the workaround in this documentation, the Related JIRA issue Visualforce page (Fetch endpoint) still remains empty/blank.

Environment
JIRA v7.6 and above
Salesforce & JIRA Server Connector v6.1.11
Diagnostics Steps
In the Developer console, you should be able to see the following error message while inspecting the page.
If you trying to copy the link into a new tab, the URL is working correctly.

Cause
This issue is caused by the Jira clickjacking protection being enabled in your Jira.
According to the Atlassian Jira 7.6.x Release Notes, Atlassian adds the X-Frame-Options
and Content-Security-Policy
security headers to each HTTP response, which causes this issue.
In particular, please refer to the Better security with X-Frame-Options section.
Workaround
For standard Windows and Linux installations
According to the Atlassian JIRA Knowledge Base, we can either disable the feature by excluding specific paths OR passing a system property.
Excluding paths
Go to your JIRA installation directory → Edit the
setenv.sh
(Linux) orsetenv.bat
(Windows) in the bin folder. → Find the section JVM_SUPPORT_RECOMMENDED_ARGS= and add the following line."-Dcom.atlassian.jira.clickjacking.protection.exclude=/plugins/servlet/customware/connector/issue/1/Case/fetch.action"
CODEIn the example line above, the system ID is "
1
". Please ensure that you have entered the correct system ID. You can locate your system ID in the Connections.You will need to log in to Jira first in the same browser session for the Visualforce page to appear.
Disabling security headers
Go to your JIRA installation directory → Edit the
setenv.sh
(Linux) orsetenv.bat
(Windows) in the bin folder. → Find the section JVM_SUPPORT_RECOMMENDED_ARGS= and add the following line."-Dcom.atlassian.jira.clickjacking.protection.disabled=true"
CODE
Please do note that the clickjacking protection will re-enable after Jira upgrade.
For Jira installed as a Windows service
Follow Atlassian's instructions for setting properties for Windows services via command line.
Resolution
N/A