Cannot load a Safari Extension onto my iPhone 15 running iOS 18.4

Question

Created Apr ’25

Replies 1

Boosts 0

Participants 2

I'm trying to load a Safari Extension onto my physical iPhone 15 running iOS 18.4 but am seeing the following message: "iOS 18.4 is not installed."

Screenshot 2025-04-07 at 11.06.09 PM.png

When I click the Get button I see that the download has failed with the following error message. I tried updating my laptop to Sequoia and I also deleted and re-installed Xcode but that didn't fix it. Any thoughts?

Screenshot 2025-04-07 at 11.05.36 PM.png

Download failed.
Domain: DVTDownloadableErrorDomain
Code: 41
User Info: {
    DVTErrorCreationDateKey = "2025-04-08 06:00:22 +0000";
}
--
Download failed.
Domain: DVTDownloadableErrorDomain
Code: 41
--
Failed fetching catalog for assetType (com.apple.MobileAsset.iOSSimulatorRuntime), serverParameters ({
    RequestedBuild = 22E238;
})
Domain: DVTDownloadsUtilitiesErrorDomain
Code: -1
--
Download failed due to a bad URL. (Catalog download for com.apple.MobileAsset.iOSSimulatorRuntime)
Domain: com.apple.MobileAssetError.Download
Code: 49
User Info: {
    checkConfiguration = 1;
}
--


System Information

macOS Version 15.4 (Build 24E248)
Xcode 16.3 (23785) (Build 16E140)
Timestamp: 2025-04-07T23:00:22-07:00

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Answer 1

Ali-Hassan-Saqer OP

Apr ’25

Hey! This usually happens when Xcode can’t fetch the simulator catalog properly. Here’s the best way to fix it:

Clean Xcode’s cache and reset the download catalog by running these in Terminal:

rm -rf ~/Library/Caches/com.apple.dt.Xcode  
rm -rf ~/Library/Developer/CoreSimulator  
defaults delete com.apple.dt.Xcode DVTFetchedAvailableDownloads

Then restart Xcode, go to Settings > Platforms, and try downloading the iOS 18.4 simulator again.

If that doesn’t work, try using the command line to force the download:

xcodebuild -downloadPlatform iOS

This bypasses the GUI and downloads it directly.

If you’re still stuck, check if there’s a newer Xcode version (like 16.4 beta or final) from Apple’s Developer website. Sometimes simulators for newer iOS versions only show up in newer Xcode builds.
As a last resort, you can manually install the simulator by copying the iOS 18.4 simulator runtime folder (iOS 18.4.simruntime) from someone else’s Mac who already has it, or extract it manually from an IPSW file.

Hope this helps get your Safari extension running!

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