MobileDevice.pkg untrusted, cannot open Xcode after OS X update

Question

Edit and set the date of your Mac as October 1st, 2019.

I didn't have Xcode 11.1 installed and even though I could open and run the 11.0 after the below workaround I could not update to 11.1 as the update always failed. So I have just re-installed the whole app from the App-Store - you could probably also do this instead of the below method.

I have tried setting my system time to 1st October 2019 when the certificate should had been still valid. After that I tried to open Xcode and followed the component install which went well and now I am able to work with Xcode again.

I had a similar problem, where I installed Xcode 11.1, and installed the components and everything within the same folder where I had Xcode 10.2.1. Then, I tried to go back to Xcode 10.2.1 and couldn't opened as it was asking me to install components again, and when I tried I was getting this error.

The package “MobileDeviceDevelopment.pkg” is untrusted.

So, the workaround that fixed it for me was navigating to...

/Users/YourUser/Applications/Xcode\ 10.2.1.app/Contents/Resources/

Then, deleting MobileDeviceDevelopment.pkg and everything went back to normal :)

I hope this helps anyone else with this issue. Cheers!

At macOS Catalina

cd /Applications/Xcode.app/Contents/Resources/Packages
sudo rm -rf MobileDevice.pkg
sudo rm -rf MobileDeviceDevelopment.pkg 

Try again. It means you entered on the Xcode downloaded packages and remove it. I really don't understand how Apple do but if you remove Xcode will download it again and revalidates.

Some remarks, I'm on XCODE Version 11.0 (11A420a) if you are not this is not guaranteed to work.