Failed to find a DDI

Question

Daniel1codes OP

Created 1w

Replies 5

Boosts 0

Participants 4

Hello!

When launching/debugging on my iPad and iPhone I keep getting the following error:

“Previous preparation error: Failed to find a DDI … Run ‘devicectl list preferredDDI’ …”

I believe this was caused by a previously interrupted Xcode update around June due to low disk space, which may have left DeviceSupport/DDI/CoreDevice files incomplete. Even after finishing the update later, the error persists. I now use a new Mac with 4 TB of storage, but the issue still occurs.

Since then I have unfortunately been blocked from testing or presenting my app on devices. It seems that only a new, fully completed Xcode update might resolve the problem.

Tried so far: – Cleared caches (CoreDevice/Devices) – Reset trust on device and re-paired – Checked devicectl list preferredDDI

I would really appreciate guidance, as at the moment I cannot present my app due to this blocking issue.

Thank you very much for your support!

Boost

Answer 1

DTS Engineer OP

Apple

6d

Can you provide the output of devicectl list preferredDDI?

— Ed Ford,  DTS Engineer

1

Answer 2

Daniel1codes OP

6d

Hi Ed, thanks for the quick reply. I tried to reply directly in the forum with the requested output, but I keep receiving an error message ("Your post couldn’t be saved. Please try again in a few minutes."). It seems I cannot currently post a follow-up reply. The output: zsh: command not found: devicectl

0

Answer 3

DTS Engineer OP

Apple

5d

I got this reply. 😀

I underspecified the exact command there, which is my mistake. The full command is xcrun devicectl list preferredDDI. What's that output?

— Ed Ford,  DTS Engineer

1

Answer 4

haptic OP

13h

Hello, Ed,

Sorry to jump in here too… ;-)

I have the same problem after upgrading to Xcode Version 26.0 (17A324).

Thanks for mentioning the full command, until now, I had never used the command line for Xcode.

The output states that several DeveloperDiskImages are too old:

file:///Library/Developer/DeveloperDiskImages/iOS_DDI/ file:///Library/Developer/DeveloperDiskImages/tvOS_DDI/ file:///Library/Developer/DeveloperDiskImages/watchOS_DDI/ file:///Library/Developer/DeveloperDiskImages/xrOS_DDI/

"incompatibleContentReason: The DDI's CoreDevice content is too old."

Is it safe to delete them — and hope/pray that they would get properly replaced automatically?

Thanks ;-)

PS: Actually, this is exactly what I will do — and see what will happen…

0

Answer 5

pax26 OP

6h

Hello @haptic! As @Daniel1codes mentioned in his reply to your last message, the best and easiest solution, is to carry out a full delete of Xcode, followed by a re-install from the App Store.

I ran into this issue when I updated to Xcode 26, so I carried out a full delete of Xcode and reinstalled from App Store. This fixed the DDI issue.

Terminal commands used to fully delete Xcode:

sudo rm -rf /Applications/Xcode.app
rm -rf ~/Library/Developer/Xcode  
rm -rf ~/Library/Caches/com.apple.dt.Xcode
rm -rf ~/Library/Developer/CoreSimulator  
rm -rf ~/Library/MobileDevice   

sudo rm -rf /Library/Developer/CommandLineTools

sudo rm -rf /Library/Developer
sudo rm -rf /System/Volumes/Data/Library/Developer

rm -rf ~/Library/Preferences/com.apple.dt.Xcode.plist
rm -rf ~/Library/Application\ Support/Xcode

NOTE: If you are getting 'Operation Not Permitted' when running sudo rm -rf /Library/Developer or sudo rm -rf /System/Volumes/Data/Library/Developer manually delete them in Finder.

1