I help a lot of developers with macOS trusted execution problems. For example, they might have an app being blocked by Gatekeeper, or an app that crashes on launch with a code signing error. If you encounter a problem that’s not explained here, start a new thread with the details. Put it in the Code Signing > General subtopic and tag it with relevant tags like Gatekeeper, Code Signing, and Notarization — so that I see it. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Resolving Trusted Execution Problems macOS supports three software distribution channels: The user downloads an app from the App Store. The user gets a Developer ID-signed program directly from its developer. The user builds programs locally using Apple or third-party developer tools. The trusted execution system aims to protect users from malicious code. It’s comprised of a number of different subsystems. For example, Gatekeeper strives to ensure that only trusted software runs on a user’s Mac, while XProtect is the platform’s built-in anti-malware technology. Note To learn more about these technologies, see Apple Platform Security. If you’re developing software for macOS your goal is to avoid trusted execution entanglements. You want users to install and use your product without taking any special steps. If, for example, you ship an app that’s blocked by Gatekeeper, you’re likely to lose a lot of customers, and your users’ hard-won trust. Trusted execution problems are rare with Mac App Store apps because the Mac App Store validation process tends to catch things early. This post is primarily focused on Developer ID-signed programs. Developers who use Xcode encounter fewer trusted execution problems because Xcode takes care of many code signing and packaging chores. If you’re not using Xcode, consider making the switch. If you can’t, consult the following for information on how to structure, sign, and package your code: Placing content in a bundle Embedding nonstandard code structures in a bundle Embedding a command-line tool in a sandboxed app Creating distribution-signed code for macOS Packaging Mac software for distribution Gatekeeper Basics User-level apps on macOS implement a quarantine system for new downloads. For example, if Safari downloads a zip archive, it quarantines that archive. This involves setting the com.apple.quarantine extended attribute on the file. Note The com.apple.quarantine extended attribute is not documented as API. If you need to add, check, or remove quarantine from a file programmatically, use the quarantinePropertiesKey property. User-level unarchiving tools preserve quarantine. To continue the above example, if you double click the quarantined zip archive in the Finder, Archive Utility will unpack the archive and quarantine the resulting files. If you launch a quarantined app, the system invokes Gatekeeper. Gatekeeper checks the app for problems. If it finds no problems, it asks the user to confirm the launch, just to be sure. If it finds a problem, it displays an alert to the user and prevents them from launching it. The exact wording of this alert varies depending on the specific problem, and from release to release of macOS, but it generally looks like the ones shown in Apple > Support > Safely open apps on your Mac. The system may run Gatekeeper at other times as well. The exact circumstances under which it runs Gatekeeper is not documented and changes over time. However, running a quarantined app always invokes Gatekeeper. Unix-y networking tools, like curl and scp, don’t quarantine the files they download. Unix-y unarchiving tools, like tar and unzip, don’t propagate quarantine to the unarchived files. Confirm the Problem Trusted execution problems can be tricky to reproduce: You may encounter false negatives, that is, you have a trusted execution problem but you don’t see it during development. You may also encounter false positives, that is, things fail on one specific Mac but otherwise work. To avoid chasing your own tail, test your product on a fresh Mac, one that’s never seen your product before. The best way to do this is using a VM, restoring to a snapshot between runs. For a concrete example of this, see Testing a Notarised Product. The most common cause of problems is a Gatekeeper alert saying that it’s blocked your product from running. However, that’s not the only possibility. Before going further, confirm that Gatekeeper is the problem by running your product without quarantine. That is, repeat the steps in Testing a Notarised Product except, in step 2, download your product in a way that doesn’t set quarantine. Then try launching your app. If that launch fails then Gatekeeper is not the problem, or it’s not the only problem! Note The easiest way to download your app to your test environment without setting quarantine is curl or scp. Alternatively, use xattr to remove the com.apple.quarantine extended attribute from the download before you unpack it. For more information about the xattr tool, see the xattr man page. Trusted execution problems come in all shapes and sizes. Later sections of this post address the most common ones. But first, let’s see if there’s an easy answer. Run a System Policy Check macOS has a syspolicy_check tool that can diagnose many common trusted execution issues. To check an app, run the distribution subcommand against it: % syspolicy_check distribution MyApp.app App passed all pre-distribution checks and is ready for distribution. If there’s a problem, the tool prints information about that problem. For example, here’s what you’ll see if you run it against an app that’s notarised but not stapled: % syspolicy_check distribution MyApp.app App has failed one or more pre-distribution checks. --------------------------------------------------------------- Notary Ticket Missing File: MyApp.app Severity: Fatal Full Error: A Notarization ticket is not stapled to this application. Type: Distribution Error … Note In reality, stapling isn’t always required, so this error isn’t really Fatal (r. 151446728 ). For more about that, see The Pros and Cons of Stapling forums. And here’s what you’ll see if there’s a problem with the app’s code signature: % syspolicy_check distribution MyApp.app App has failed one or more pre-distribution checks. --------------------------------------------------------------- Codesign Error File: MyApp.app/Contents/Resources/added.txt Severity: Fatal Full Error: File added after outer app bundle was codesigned. Type: Notary Error … The syspolicy_check isn’t perfect. There are a few issues it can’t diagnose (r. 136954554, 151446550). However, it should always be your first step because, if it does work, it’ll save you a lot of time. Note syspolicy_check was introduced in macOS 14. If you’re seeing a problem on an older system, first check your app with syspolicy_check on macOS 14 or later. If you can’t run the syspolicy_check tool, or it doesn’t report anything actionable, continue your investigation using the instructions in the following sections. App Blocked by Gatekeeper If your product is an app and it works correctly when not quarantined but is blocked by Gatekeeper when it is, you have a Gatekeeper problem. For advice on how to investigate such issues, see Resolving Gatekeeper Problems. App Can’t Be Opened Not all failures to launch are Gatekeeper errors. In some cases the app is just broken. For example: The app’s executable might be missing the x bit set in its file permissions. The app’s executable might be subtly incompatible with the current system. A classic example of this is trying to run a third-party app that contains arm64e code on systems prior to macOS 26 beta. macOS 26 beta supports arm64e apps directly. Prior to that, third-party products (except kernel extensions) were limited to arm64, except for the purposes of testing. The app’s executable might claim restricted entitlements that aren’t authorised by a provisioning profile. Or the app might have some other code signing problem. Note For more information about provisioning profiles, see TN3125 Inside Code Signing: Provisioning Profiles. In such cases the system displays an alert saying: The application “NoExec” can’t be opened. [[OK]] Note In macOS 11 this alert was: You do not have permission to open the application “NoExec”. Contact your computer or network administrator for assistance. [[OK]] which was much more confusing. A good diagnostic here is to run the app’s executable from Terminal. For example, an app with a missing x bit will fail to run like so: % NoExec.app/Contents/MacOS/NoExec zsh: permission denied: NoExec.app/Contents/MacOS/NoExec And an app with unauthorised entitlements will be killed by the trusted execution system: % OverClaim.app/Contents/MacOS/OverClaim zsh: killed OverClaim.app/Contents/MacOS/OverClaim In some cases running the executable from Terminal will reveal useful diagnostics. For example, if the app references a library that’s not available, the dynamic linker will print a helpful diagnostic: % MissingLibrary.app/Contents/MacOS/MissingLibrary dyld[88394]: Library not loaded: @rpath/CoreWaffleVarnishing.framework/Versions/A/CoreWaffleVarnishing … zsh: abort MissingLibrary.app/Contents/MacOS/MissingLibrary Code Signing Crashes on Launch A code signing crash has the following exception information: Exception Type: EXC_CRASH (SIGKILL (Code Signature Invalid)) The most common such crash is a crash on launch. To confirm that, look at the thread backtraces: Backtrace not available For steps to debug this, see Resolving Code Signing Crashes on Launch. One common cause of this problem is running App Store distribution-signed code. Don’t do that! For details on why that’s a bad idea, see Don’t Run App Store Distribution-Signed Code. Code Signing Crashes After Launch If your program crashes due to a code signing problem after launch, you might have encountered the issue discussed in Updating Mac Software. Non-Code Signing Failures After Launch The hardened runtime enables a number of security checks within a process. Some coding techniques are incompatible with the hardened runtime. If you suspect that your code is incompatible with the hardened runtime, see Resolving Hardened Runtime Incompatibilities. App Sandbox Inheritance If you’re creating a product with the App Sandbox enabled and it crashes with a trap within _libsecinit_appsandbox, it’s likely that you’re having App Sandbox inheritance problems. For the details, see Resolving App Sandbox Inheritance Problems. Library Loading Problem Most library loading problems have an obvious cause. For example, the library might not be where you expect it, or it might be built with the wrong platform or architecture. However, some library loading problems are caused by the trusted execution system. For the details, see Resolving Library Loading Problems. Explore the System Log If none of the above resolves your issue, look in the system log for clues as to what’s gone wrong. Some good keywords to search for include: gk, for Gatekeeper xprotect syspolicy, per the syspolicyd man page cmd, for Mach-O load command oddities amfi, for Apple mobile file integrity, per the amfid man page taskgated, see its taskgated man page yara, discussed in Apple Platform Security ProvisioningProfiles You may be able to get more useful logging with this command: % sudo sysctl -w security.mac.amfi.verbose_logging=1 Here’s a log command that I often use when I’m investigating a trusted execution problem and I don’t know here to start: % log stream --predicate "sender == 'AppleMobileFileIntegrity' or sender == 'AppleSystemPolicy' or process == 'amfid' or process == 'taskgated-helper' or process == 'syspolicyd'" For general information the system log, see Your Friend the System Log. Revision History 2025-08-06 Added the Run a System Policy Check section, which talks about the syspolicy_check tool (finally!). Clarified the discussion of arm64e. Made other editorial changes. 2024-10-11 Added info about the security.mac.amfi.verbose_logging option. Updated some links to point to official documentation that replaces some older DevForums posts. 2024-01-12 Added a specific command to the Explore the System Log section. Change the syspolicy_check callout to reflect that macOS 14 is no longer in beta. Made minor editorial changes. 2023-06-14 Added a quick call-out to the new syspolicy_check tool. 2022-06-09 Added the Non-Code Signing Failures After Launch section. 2022-06-03 Added a link to Don’t Run App Store Distribution-Signed Code. Fixed the link to TN3125. 2022-05-20 First posted.

Background We are using a Developer ID application certificate to sign our application. We lost the private key and we need to revoke it before we can receive a new one. Per documentation (https://developer.apple.com/support/certificates/), I know that previously installed applications will still be able to run, but new installations will not be able to work. I want to confirm what will happen when we revoke the certificate so we know how to prepare customers for this upcoming change. Questions Will existing installations of the application receive a notice that the certificate has been revoked? Will previously installed applications be able to launch again after they are closed? What will the user see when they try to install the application with the revoked certificate?

IMPORTANT The underlying issue here (FB8830007) was fixed in macOS 11.3, so the advice in this post is irrelevant if you’re building on that release or later. Note This content is a repost of info from another thread because that thread is not world readable (it’s tied to the DTK programme). A number of folks have reported problems where: They have a product that supports older versions of macOS (anything prior to 10.11). If they build their product on Intel, everything works. If they build their product on Apple Silicon, it fails on those older versions of macOS. A developer filed a bug about this (FB8830007) and, based on the diagnosis of that bug, I have some info to share as to what’s going wrong and how you can prevent it. Let’s start with some background. macOS’s code signing architecture supports two different hash formats: sha1, the original hash format, which is now deprecated sha256, the new format, support for which was added in macOS 10.11 codesign should choose the signing format based on the deployment target: If your deployment target is 10.11 or later, you get sha256. If your deployment target is earlier, you get both sha1 and sha256. This problem crops up because, when building for both Intel and Apple Silicon, your deployment targets are different. You might set the deployment target to 10.9 but, on Apple Silicon, that’s raised to the minimum Apple Silicon system, 11.0. So, which deployment target does it choose? Well, the full answer to that is complex but the executive summary is that it chooses the deployment target of the current architecture, that is, Intel if you’re building on Intel and Apple Silicon if you’re building on Apple Silicon. For example: intel% codesign -d --arch x86_64 -vvv Test664892.app … Hash choices=sha1,sha256 … intel% codesign -d --arch arm64 -vvv Test664892.app … Hash choices=sha1,sha256 … arm% codesign -d --arch x86_64 -vvv Test664892.app … Hash choices=sha256 … arm% codesign -d --arch arm64 -vvv Test664892.app … Hash choices=sha256 … The upshot is that you have problems if your deployment target is less than 10.11 and you sign on Apple Silicon. When you run on, say, macOS 10.10, the system looks for a sha1 hash, doesn’t find it, and complains. The workaround is to supply the --digest-algorithm=sha1,sha256, which overrides the hash choice logic in codesign and causes it to include both hashes: arm% codesign -s - --digest-algorithm=sha1,sha256 Test664892.app arm% codesign -d --arch x86_64 -vvv Test664892.app … Hash choices=sha1,sha256 … % codesign -d --arch arm64 -vvv Test664892.app … Hash choices=sha1,sha256 … Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"

To ship a product outside of the Mac App Store, you must notarise it. The notary service issues a notarised ticket, and the ultimate consumer of that ticket is Gatekeeper. However, Gatekeeper does not just check the ticket; it also applies a variety of other checks, and it’s possible for those checks to fail even if your notarised ticket is just fine. To avoid such problems showing up in the field, test your product’s compatibility with Gatekeeper before shipping it. To do this: Set up a fresh machine, one that’s never seen your product before. If your product supports macOS 10.15.x, x < 4, the best OS version to test with is 10.15.3 [1]. Download your product in a way that quarantines it (for example, using Safari). Disconnect the machine from the network. It might make sense to skip this step. See the discussion below. Install and use your product as your users would. If the product is signed, notarised, and stapled correctly, everything should work. If not, you’ll need to investigate what’s making Gatekeeper unhappy, fix that, and then retest. For detailed advice on that topic, see Resolving Trusted Execution Problems. Run this test on a fresh machine each time. This is necessary because Gatekeeper caches information about your product and it’s not easy to reset that cache. Your best option is to do this testing on a virtual machine (VM). Take a snapshot of the VM before the first test, and then restore to that snapshot when you want to retest. Also, by using a VM you can disable networking in step 3 without disrupting other work on your machine. The reason why you should disable networking in step 3 is to test that you’ve correctly stapled the notarised ticket on to your product. If, for some reason, you’re unable to do that stapling, it’s fine to skip step 3. However, be aware that this may cause problems for a user if they try to deploy your product to a Mac that does not have access to the wider Internet. For more background on this, see The Pros and Cons of Stapling. [1] macOS 10.15.4 fixes a bug that made Gatekeeper unnecessarily strict (r. 57278824), so by testing on 10.15.3 you’re exercising the worst case. The process described above is by far the best way to test your Gatekeeper compatibility because it accurately tests how your users run your product. However, you can also run a quick, albeit less accurate test, using various command-line tools. The exact process depends on the type of product you’re trying to check: App — Run syspolicy_check like this: % syspolicy_check distribution WaffleVarnish.app This tool was introduced in macOS 14. On older systems, use the older spctl tool. Run it like this: % spctl -a -t exec -vvv WaffleVarnish.app Be aware, however, that this check is much less accurate. Disk image — Run spctl like this: % spctl -a -t open -vvv --context context:primary-signature WaffleVarnish.dmg Installer package — Run spctl like this: % spctl -a -t install -vvv WaffleVarnish.pkg Other code — Run codesign like this: % codesign -vvvv -R="notarized" --check-notarization WaffleVarnish.bundle This command requires macOS 10.15 or later. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Revision history: 2024-12-05 Added instructions for using syspolicy_check. Made other minor editorial changes. 2023-10-20 Added links to Resolving Trusted Execution Problems and The Pros and Cons of Stapling. Made other minor editorial changes. 2021-02-26 Fixed the formatting. 2020-04-17 Added the section discussing spctl. 2020-03-25 First version.