Xcode doesn't support iOS 14.5.1

You can add support for iOS 14.5 (and watchOS 7.4) by copying the relevant DeviceSupport folders from Xcode 12.5 to Xcode 12.4.
For example the one for iOS 14.5 is located at is Xcode.app/Contents/Developer/iPhoneOS.platform/DeviceSupport/14.5
You can download the xip for Xcode 12.5 from here: https://developer.apple.com/download/more/?=xcode and extract that folder from the XCode.app inside it and move it to your installed XCode.app.

There are also publicly hosted GitHub repositories with these folders, a quick search will turn them up. It is obviously better to extract it from the official source yourself, but I think the archives are signed anyways.

Xcode 12.5 is required to developer with an iOS 14.5 device. The supported combinations of Xcode versions and iOS versions is documented on the Xcode support page. Any other method of getting files to make this work with older Xcode versions is unsupported.

He's asking for iOS 14.5.1, not iOS 14.5, edford.

robske_110's response was very helpful, but two notes:

1. robske_110 missed "Platforms" in the directory path: It's Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/14.5

2. Be sure to use the Finder to copy the directory. I used the command line the first time (sudo cp -r …), and Xcode didn't like it. I don't remember if it was a different error message than the unsupported iOS version, but it didn't work. (Yes, I quit Xcode before copying, then started Xcode again.) After doing the same thing through the Finder, it worked. The next time running the app from Xcode still took a little extra time; it said something about copying cache files to my phone; I assume that's related to the 14.5 stuff I just added with the above instructions.

Also, ferFrassia mentioned 14.5.1 vs. 14.5. It looks like that DeviceSupport directory only has X.Y versions, not X.Y.Z. My iPhone is currently running 14.5.1, and copying the 14.5 folder fixed it (using Xcode 12.4 under Catalina/10.15.7).

Thanks, all (especially robske_110) for the help!

It looks like catilina support is dropped for 14.5?

Above response is helpful to identify iOS 14.5.1 device using Xcode12.4, but Xcode 12.4 is not supporting debug options. Unable to debug tests. Once script reaches breakpoint i am getting error message "Lost connection to the debugger on..{device name}" and unable to proceed further.Is there any way to fix this issue?

I can't update Xcode in Catalina, it requires macOS 11.0 or later, therefore I can't run iOS 14.5. Seems I will have to update to my mac to Big Sur first...

Just installed Xcode 12.5. I'm on Big Sur. Can't run devices on 14.5.1. Says device is unsupported. "Failed to prepare device for development" in Devices. So what now? Do I just not work until the release of a new Xcode? iPhone 12 came with 14.5.1 installed so this wasn't my choice at all. This is frustrating.

Just restarted both devices, and device run passes for me now. (iOS 14.5.1. and Xcode 12.5)

I'm having the exact same problem as vasistavama .

Just to pile on, my configuration is:

MBP 2016 running MacOS 11.3.1 (Big Sur)
iPhone XS running release iOS 14.5.1
Xcode 12.5

...and I get the "Failed to prepare device for development" error. Frustrating!

Xcode 12.5 won't run on Catalina but I have a super old Mac from 2012 so this won't be able to upgrade to MacOS 11.0 Big Sur. Any suggestion? :( I already updated my IOS

Similar problem...my iPhone/iPad auto updated, and now it effectively turned my 27 inch 2013 iMac into a useless development tool. This is beyond frustrating. One expensive OS upgrade just stalled years of work..

In fact. This is a too expensive environment for casual developers like me. :-(

Apple should learn a lot of thing from Microsoft and Google About backward compatible

in windows 10 or 11 you can install any version of visual studio since 1996