After performing an upgrade, the Citrix Gateway login page or either the Citrx ADC or the Citrix Gateway GUI management page show blank/white page.

The issue can, sometimes, be observed even setting the Gateway custom theme to "default" before the upgrade.

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Option 1:

If previously the "httpd.conf" file was modified, as suggested in https://support.citrix.com/article/CTX255947

1. Ensure you have the local copy of the original /etc/httpd.conf
2. Delete the /etc/httpd.conf
3. Delete the /nsconfig/httpd.conf
4. Copy your local copy of httpd.conf to /etc/httpd.conf and /nsconfig/httpd.conf You can also copy the file from a different Citrix ADC or Gateway running the same version and build.
5. Reboot the appliance.

Option 2

If there is a Custom Login Theme globally bound as described in https://docs.citrix.com/en-us/netscaler-gateway/12/vpn-user-config/custom-portal.html#a-note-on-older-portal-customizations

1. Downgrade to the previous version
2. On the Configuration tab, Navigate to Citrix Gateway > Global Settings.
3. Click Change Global Settings.
4. Click the Client Experience tab.
5. Scroll to the bottom of the screen then select DEFAULT from the UI Theme list.
6. Click OK.
7. Proceed to upgrade again.

Refer to Citrix Documentation for detailed information on upgrades: https://docs.citrix.com/en-us/citrix-adc/12-1/upgrade-downgrade-citrix-adc-appliance/troubleshooting.html
 

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Problem Cause

Manual modification on any of the login theme files.