Fixed: Unreal Engine 5.4.4 install failed around 70%, Xcode not detected, then crash on MacBook Air M1 / macOS Sequoia
I was finally able to install and launch Unreal Engine 5.4.4 on my MacBook Air M1 running macOS Sequoia after running into a few different problems.
I’m posting the full sequence because the error messages were a bit misleading. If I had to install Unreal again on this machine, this is what I would check/do first. This will probably work for most versions, I’ve used 5.4.4 on my air because 5.7 might be too demanding for my prototype.
- If the install fails around 70% with “file corruption”
My install was failing at around 71% with:
Install Failed
A file corruption has occurred. Please try again.
Error Code: IS-IN-FC02
What fixed it for me was launching the Epic Games Launcher with a higher open-file limit.
First, close the Epic Games Launcher completely.
Then open Terminal and run:
sudo sysctl -w kern.maxfiles=131072 kern.maxfilesperproc=65536
Then launch Epic Games Launcher from the same Terminal session with:
ulimit -S -n 65536 && open -a "Epic Games Launcher"
After that, I went back to the Unreal Engine install in the Epic Games Launcher and clicked Resume.
This allowed the installation to continue successfully.
My guess is that the installer was hitting macOS file descriptor limits while unpacking/verifying a very large number of files, and Epic reported it as “file corruption,” even though the files themselves may not have been the real problem.
2. If Unreal says “Xcode Not Found” even though Xcode is installed
After the install, Unreal failed to launch and showed:
Xcode Not Found
Unreal Engine requires Xcode to compile shaders for Metal.
But I already had both Xcode and the Command Line Tools installed.
When I checked:
xcode-select -p
It returned:
/Library/Developer/CommandLineTools
So macOS was pointing developer tools to the standalone Command Line Tools folder instead of the full Xcode app.
Trying this also failed:
sudo xcodebuild -license
with:
xcode-select: error: tool 'xcodebuild' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance
The fix was:
sudo xcode-select -s /Applications/Xcode.app/Contents/Developer
Then I verified/accepted the Xcode license:
sudo xcodebuild -license
After that, Unreal detected Xcode correctly.
3. If Unreal crashes with “Bad CPU type in executable”
After fixing Xcode, Unreal started launching but then crashed with:
Fatal error: FMacPlatformProcess::CreateProc: posix_spawn() failed (86, Bad CPU type in executable)
The important part is:
Bad CPU type in executable
Since this is an Apple Silicon Mac, that suggested something inside Unreal or one of its helper tools was trying to run an Intel/x86_64 executable, but Rosetta was not installed.
The fix was:
softwareupdate --install-rosetta --agree-to-license
After installing Rosetta, Unreal Engine 5.4.4 launched successfully.
Final sequence I would use next time
So if I had to install Unreal Engine again on an Apple Silicon Mac, I would do this:
# Make sure macOS developer tools point to full Xcode, not only Command Line Tools
sudo xcode-select -s /Applications/Xcode.app/Contents/Developer
# Accept the Xcode license
sudo xcodebuild -license
# Install Rosetta, needed by some Intel helper binaries
softwareupdate --install-rosetta --agree-to-license
# Optional but useful if Epic install fails around 70% with "file corruption"
sudo sysctl -w kern.maxfiles=131072 kern.maxfilesperproc=65536
ulimit -S -n 65536 && open -a "Epic Games Launcher"
Then resume the Unreal Engine installation from the Epic Games Launcher.
This fixed the install and launch problems for me on:
MacBook Air M1 8GB RAM
macOS Sequoia 15.7.4
Unreal Engine 5.4.4
Hope this helps someone else who runs into the same combination of issues. This will probably work on newer versions too.