The root certificate of the signature in the app package or bundle must be trusted

I am working on mobile application development for which I am using Xamarin with Visual studio 2017. I have created a package for UWP(Universal Windows Platform) platform for windows mobile app, which I tested on my local machine by installing it which is working fine. However, when I have given this entire package(appxbundle etc.) to other user for testing, on there machine it is giving the following error while installing.

Error 0x800B0109 :The root certificate of the signature in the app package or bundle must be trusted.

SO what is the reason the same package works on one machine and not on the other ? Any help on this appreciated !

It works on your device because you have already run it via debugger so the app certificate is already installed.

To make it work on someone else's device you either need to install via Powershell, which handles the certficate installation (right-click the ps1 file which comes along with the package and Run with Powershell) or you first have to install the certifiate manually by double-clicking the certificate file in the _Test folder.