Hello. I have a couple questions that will help determine/troubleshoot what may be causing the error. Can you share what Software/Firmware version is running on the WC7855? What application were you attempting to install when you received the error? Are you attempting to install from the device or from the App Studio/App Gallery website? Can you share a screen capture of the error message? In your second post, did you enable the Security Installation Policy or was it already enabled? If you enabled it, did that resolved the install issue? Thank you!