Unable to download iOS simulator runtime 26.x on Xcode

Thanks for your post.

It appears that you are experiencing difficulties downloading the iOS 26 simulator runtime, which is hindering your ability to compile and test your code. Are you utilizing the most recent version of Xcode from the App Store? The versions on your log file show that you are. The issue seems to be related to a network connection. As it seems can dns com.apple.MobileAsset.iOSSimulatorRuntime?

Please ensure that your network connection is stable and that there are no firewalls or network settings obstructing access to Apple’s servers. The error messages indicate a failure to establish a connection to a host, which may be attributed to network-related issues.

Although your setup appears compatible, it is advisable to verify that macOS 26.1 and Xcode 26.2 are fully updated. Occasionally, point updates can resolve unforeseen issues with downloads or simulator installations.

Attempt restarting your router, modem, and Mac to eliminate any temporary network glitches that may be interfering with connections to Apple’s servers.

If you are connected to a proxy or corporate network, ensure that your Mac’s network settings are correctly configured to permit connections to Apple domains. Temporarily disabling the proxy can also assist in diagnosing whether it is causing the issue. Examine Xcode logs for more detailed error information. You can locate these logs in or by utilizing the Console application to filter logs related to Xcode.

Have you tried it from a different location?

Albert Pascual
  Worldwide Developer Relations.

@DTS Engineer

Thank you for the reply, I have tried resetting my router, restarting my Mac, and also tried different networks. But it's the same issue.

I don't have firewall or Anti virus installed and still same error.

Xcode is fully updated (latest)

MacOS is Tahoe 26.1 (latest)

As you can see, using cli still throws similar error

➜  ~ xcodebuild -downloadPlatform iOS      
Finding content...
Automatically resolved architecture variant for platform iOS as 'arm64'.
2026-01-07 22:09:14.742 xcodebuild[71859:6206960]  DVTDownloadable: Download Failed. Downloadable: {
    architectures =     (
        arm64
    );
    authentication = none;
    category = simulator;
    contentType = cryptexDiskImage;
    dictionaryVersion = 2;
    downloadMethod = mobileAsset;
    fileSize = 8388683973;
    identifier = "com.apple.dmg.iPhoneSimulatorSDK26_2_arm64";
    isInternalContent = 0;
    isUserInitiated = 1;
    name = "iOS 26.2 Simulator (23C54)";
    patchableFrom =     (
    );
    platform = "com.apple.platform.iphoneos";
    simulatorVersion =     {
        buildUpdate = 23C54;
        version = "26.2";
    };
    version = "26.2.0.0";
}. Download failed.
➜  ~ 

Note: there's no iOS 26.x Simulator at https://developer.apple.com/download/all/?q=26.2 as opposed to previous versions which can be found here.

I am experiencing the same issue as are many others, therefore it's unlikely to be a local network or system issue.

It looks more like an Apple network or CDN config issue.

Download failed as the server said it was a bad request. (Asset download for com.apple.MobileAsset.iOSSimulatorRuntime e4478b4b9014ff28fe3c265daca488f55a284f4c) Downloading iOS 26.2 Simulator (23C54) (arm64): Error: Error Domain=DVTDownloadsUtilitiesErrorDomain Code=-1 "Download failed as the server said it was a bad request. (Asset download for com.apple.MobileAsset.iOSSimulatorRuntime e4478b4b9014ff28fe3c265daca488f55a284f4c)" UserInfo={NSUnderlyingError=0x6000014aa580 {Error Domain=com.apple.MobileAssetError.Download Code=40 "Download failed as the server said it was a bad request. (Asset download for com.apple.MobileAsset.iOSSimulatorRuntime e4478b4b9014ff28fe3c265daca488f55a284f4c)" UserInfo={NSLocalizedDescription=Download failed as the server said it was a bad request. (Asset download for com.apple.MobileAsset.iOSSimulatorRuntime e4478b4b9014ff28fe3c265daca488f55a284f4c), checkConfiguration=true}}, NSLocalizedDescription=Download failed as the server said it was a bad request. (Asset download for com.apple.MobileAsset.iOSSimulatorRuntime e4478b4b9014ff28fe3c265daca488f55a284f4c), DetailedAssetAttributes=Failed downloading asset with attributes ({ Architectures = ( arm64 ); ArchiveDecryptionKey = "2DYVQ3nImChvmjNXYnGUy0b+gQKHwr2YXnMo/CjcSE0="; ArchiveID = "S4/QPQeJfaTevGsiFxetZjcvpMAuUoJrkiLXXeNARCs="; AssetFormat = AppleArchive; AssetType = "com.apple.MobileAsset.iOSSimulatorRuntime"; Build = 23C54; Ramp = 0; SimulatorVersion = "26.2"; TrainName = LuckC; "_CompressionAlgorithm" = AppleArchive; "_DownloadSize" = 8388608000; "_Measurement" = {length = 20, bytes = 0x9c93e171a2b8792b9988dd9b44621dc2efb8a3dc}; "_Measurement-SHA256" = {length = 32, bytes = 0x282fa56b c46cd445 b8709fa9 3c720915 ... c56f4284 351baf1a }; "_MeasurementAlgorithm" = "SHA-1"; "_UnarchivedSize" = 8381083648; "__AssetDefaultGarbageCollectionBehavior" = NeverCollected; "__BaseURL" = "https://updates.cdn-apple.com/2025/mobileassets/094-34645/AAEDD290-8894-4C50-AFA8-34D3F40B76B3/"; "__CanUseLocalCacheServer" = 1; "__RelativePath" = "com_apple_MobileAsset_iOSSimulatorRuntime/6AF3CC0B-EFC5-41D9-9F53-21E03072E041.aar"; })}

System Information

macOS Version 15.7.1 (Build 24G231) Xcode 26.2 (24553) (Build 17C52)

After clearing every cache I could think of I finally just reset the UI with

defaults delete com.apple.dt.Xcode 2>/dev/null || true

On restarting Xcode I had to re add my account but I could then download the iOS Simulator 26.2 runtime.

Had it myself for some time. Same exact error message. The cause was my /etc/hosts file.

cat /etc/hosts | grep apple

I had there:

0.0.0.0 gdmf.apple.com

I don't have any idea how it got there, but it was there and it blocked my computer from reaching Apple servers. Commenting that 1 line resolved the issue for me.

Make sure your computer doesn't block connection to gdmf.apple.com in any other way.

For anyone else facing this:

Disabling all my VPNs fixed this for me

I'm on a company computer, some VPNs were enabled by default

Disabling them allowed the download to proceed as normal