This article is intended for Citrix administrators and technical teams only. Non-admin users must contact their company’s Help Desk/IT support team and can refer to CTX297149 for more information.


New users after installing Citrix Receiver 12.7 or above for Mac on macOS High Sierra when launching an application or desktop might get the following error:

With macOS 10.13 High Sierra, Apple has introduced a new feature, where user approval is required to load any newly-installed third-party kernel extensions (KEXTs). Citrix Receiver 12.7 for Mac requires Citrix kernel extension to be loaded for Generic USB Redirection to function properly.
If users see the “System Extension Blocked” prompt when launching a Citrix Receiver desktop or application, they can go directly to System Preferences > Security & Privacy and Click Allow against Citrix Systems Inc as shown below to allow loading of the Citrix kernel extension:


Users can also go to the Devices tab in Citrix Receiver Preferences and follow the steps as shown below in the screenshot:


In addition, users can also open preferences from the Devices tab on the Desktop toolbar or the USB Devices menu in the main Citrix Viewer menu as shown below: