Unable to install to device

Trying to test load on an iPad Pro
I have upgraded Xcode to 12.3
Upgraded the iPad to 14.3
Upgraded Xojo to 2020R2.1
Unticked ‘build for App Store’
Built the APP

Online: I have created an identifier, matching the bundle ID and appname.
(com.mysite.appname for appname)
Created a provisioning profile, for all my devices.
Downloaded this, double clicked it

Opened Xcode, went to Window/Devices
Selected the device, clicked +
Tried to install the app

I get ‘Unable to install’ message, but no reasons behind it, and I have run out of hoops to jump through.

Anyone have an idea what God I need to slaughter a lamb for today?

I had to create all of the certificates in Xcode. Preferences->Accounts and then create an Apple Development Certificate, iOS Distribution Certificate, Developer ID Application Certificate, and an Developer ID Installer Certificate. I found that trying to do these manually through the website didn’t work for some reason.

If that doesn’t work I create a blank iOS project in Xcode and set everything up and then let it fix things for me. It’s a pain because “unable to install” is such a non-meaningful error.

I remember doing that in older XCodes.
I cannot currently find the options to create these things in the newer Xcode screens.

Um…Preferences->Accounts. Select your account and in the lower right there’s a Manage Certificates button that brings up a dialog to create all of those different types.

No effect so far.
I can create an Xcode project with the same bundle ID and it installs and runs in debug mode in Xcode
But I cant replace it with a build from Xojo.

Used Apple Configurator.
The package is now ‘in place’ but wont launch: the icon is visible but darkened.
The iPad gives a refusal because the package ‘integrity cannot be verified’

I had this happen recently and it was an expired provisioning profile. I recommend checking everything in App Store Connect. Also, make sure your Build settings are correct in Xojo.

That was my first thought but the provisioning profile was generated brand new today, for a bundle ID that didn’t exist yesterday.
Best suggestions are ‘kill off all certificates and profiles and download them’
But I have a major update for a MacOS app to ship after Xmas and cannot afford to break that build process.

(Apple development Rule Number 1: “Change anything, break everything”)