I recently updated to Xcode 11.4.1, before this everything was fine. After I updated and built the project I got this error:
When I click it shows me this message:
And as the message says, I went to the file Assets.xcassets and get info to grant permission to all users to read and write. This did nothing, the error still appears and I'm unable to run my project.
I dint had same error with different message:
failed to read asset tags: the command (...) exited with status 1
Later I found out that there was "unusal merge conflict" in content.json file in few of images in Assets.xcassets.
I fixed this by referencing this webpage
https://osxdaily.com/2018/10/09/fix-operation-not-permitted-terminal-error-macos/
Basically you don't have permission to access all the filesystem Xcode by default in later versions of OS X.
