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Horizon ThinApp Packages Generating Prompt

Launching a ThinApp from Horizon Shows a Prompt for the First Time:

Do you or your users get an error “Do you want to allow this website to open a program on your computer?” prompt the first time they go to launch a ThinApp package in Horizon?

In most cases, the prompt is not a big deal for Horizon users on a Windows system where ThinApp packages are being deployed. But if you have a dynamic desktop environment where users are dynamically assigned a virtual system or randomly use physical desktops, this could be an issue.



First, it’s important to note, this is not a Horizon or ThinApp specific issue. Rather it’s a security configuration within Windows.

Here is how to resolve this issue. Simply create a GPO with a custom registry value or manually edit the registry of your virtual desktop master gold image to have the following registry setting within.

Registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Internet Explorer\ProtocolExecute\horizon

Create a DWORD called “WarnOnOpen” and set the value to “00000000”.

The MSDN Blog article “URL Protocols, Application Protocols, and Asynchronous Pluggable Protocols. Oh My!” explains this behavior and the fix under the Application Protocol section within Windows, which is basically what Horizon is using when it launches a ThinApp package.

This entry was posted in Horizon 1.5, ThinApp and tagged , on by .
Dean Flaming

About Dean Flaming

Dean is currently an EUC Architect and member of the VMware End User Computing Enablement and Lighthouse Support teams, working to develop communications and IP around VMware End User Computing products and solutions as well as support many various Lighthouse accounts with their own EUC practices. Prior to this, from 2008 through 2012 Dean was one of VMware's End User Computing Specialists. Throughout his time at VMware, Dean has also written and published various articles, videos, and podcasts regarding VMware's EUC Solutions.