With many customers upgrading to Citrix StoreFront – I have been asked several times how you go about getting older Presentation Server 4 farms (Yes, its still out there!!) to work and present the apps inside your StoreFront.
Don’t forget these apps , operating systems and the PS4 platform will be long out of support, but still in use for legacy reasons.
The same fix applies for Web Interface 5.4 and comes from two settings that you need to change – which refer to Launch References.
So, to fix this – If using Web Interface:
Go to your WebInterface.conf on your web interface site – eg:
C:\inetpub\wwwroot\Citrix\XenApp\conf\WebInterface.conf
and change RequireLaunchReference and OverrideIcaClientname to Off and On respectively:
RequireLaunchReference=off
OverrideIcaClientname=on
If using StoreFront:
C:\inetpub\wwwroot\Citrix\Store\web.config – and search for the two settings – set the same.
ColinRainey 
Could I just ask… where abouts do you make the RequireLaunchReference and OverrideIcaClientname changes? Is this on the Legacy environment or the new Storefront environment?
Hello Lee,
This is all done on the local Web Interface or StoreFront server, you should not need to make any changes on the old Citrix farms.
If your installing a new WebI or SF, and want to access published apps from older Presentation Server 4 (or earlier!) ,without this you may see icons, but not get connected.
regards
Colin
I have done this noticed once you launch an app on 4.0 farm, launch app on 7.6 farm fails. need to connect to another gateway launch 7.6 app and logon to original gateway and it all works until you launch a 4.0 app. really strange behaviour
Hi Rob,
What happens when you are using internally via Storefront web or Receiver? Check in Store settings that there are two separate farms with their controllers seperate and not in same list. If you can narrow it down internally external should work ok. Check the events on the Storefront for any XML or broker related issues.