error: the replacement path doesn't exist:

I do not have 18.1 Beta 6.

I started seeing the same issue after restructuring / refactoring some of my Swift projects - all of them relying on newly introduced @Macro syntax elements.

Good news: the error is unrelated to SwiftData and the crashes described further down in this thread are also unrelated to it (neither of my projects uses SwiftData so QED). I believe people are just seeing it more frequent on Xcode 16 + SwiftData because of the heavy use of Macros it introduced.

Using "Product" > "Clean Build Folder.." didn't solve the issue, however what did was the following:

• "Product" > "Show Build Folder in Finder"
• navigate up until you're in XCode's "DerivedData" folder
• find and delete all folders starting with your Projects Name + some random identifier
• restart Xcode
• rebuild

So for example my project was called "GPS.io" and the folder was named something like "GPS.io-gsytifiksezewoesjjyadyzossvf" located in "/Users/USERNAME/Library/Developer/Xcode/DerivedData"

[EDIT] I'm on XCode 16.0 (16A242d) and testing against iOS 18.0

Fixed by cleaning XCode's "DerivedData" folder. from the terminal just run this command

rm -rf ~/Library/Developer/Xcode/DerivedData

I'm still seeing the issue on Xcode 16.1 and iOS 18.1.

i have same problem when i get more than one instance of @ModelActor , if i generate single instance and share between tasks, problem solved. Bu this method not best practice!

Someone know solution ?

I have also hit this issue (and continue to do so despite trying all the suggestions made so far). I have clicked on the feedback link, but then just get a feedback not found screen. Has the link changed. Please can you advise?