"ArchiCAD 29 Add-On not loading on macOS 26 Tahoe – code signing / validation issue"

[BFG]

Hello,

I am developing an ArchiCAD 29 Add-On for macOS, and I am unable to get it to load in ArchiCAD. I would appreciate guidance on the correct code signing approach for local development.

Environment

• macOS 26.5.1 Tahoe (25F80)
• Xcode 26.5 (Build 17F42)
• ArchiCAD 29, build 4006 (Norwegian)
• API Development Kit 29.3100
• CMake 4.3.3
• Built using archicad-addon-cmake template from GitHub

What works

• The Add-On compiles successfully with both CMake and Xcode
• MDID is set with a registered Developer ID (930232405) and Local ID
• The bundle appears in Add-On Manager without a validation error icon in some sessions
• In one session, all three custom AddOnCommands worked correctly via the JSON API (port 19723)

The problem

The Add-On does not load reliably. After restarting ArchiCAD, the bundle is not loaded into process memory (verified with lsof), and all ExecuteAddOnCommand calls return error 4010 ("command not found").

We have tried the following signing approaches, none of which result in the Add-On loading consistently:

• Ad-hoc signing (codesign -s -)
• Apple Development certificate (Personal Team, free Apple ID)
• Building with AC_ADDON_FOR_DISTRIBUTION=ON
• Placing the bundle in Add-Ons/, Add-Ons/Goodies/ and Add-Ons/Local/
• Disabling Gatekeeper ("Allow apps from anywhere")
• Removing all quarantine flags with xattr -rd com.apple.quarantine

Observation

All Add-Ons that load successfully in our ArchiCAD installation are signed with Team ID 3E9E9FN277 (GRAPHISOFT) with flags=0x10000(runtime). Our bundle has a different Team ID and flags=0x0(none). We suspect macOS 26 Tahoe has introduced stricter validation requirements that prevent third-party Add-Ons from loading without a specific signing configuration.

Questions

1. What is the correct code signing approach for local development of ArchiCAD 29 Add-Ons on macOS 26 Tahoe?
2. Is a paid Apple Developer Program membership ($99/year) required for Add-On development, or is there a supported workflow for unsigned/ad-hoc signed Add-Ons?
3. Does ArchiCAD 29 maintain a blacklist of Add-Ons that have previously crashed, and if so, how can this be reset?
4. Are there any known issues with Add-On loading on macOS 26 Tahoe?

[Ralph Wessel]

Have you seen any alerts from macOS explicitly stating that the add-ons have not been signed correctly? Or is the loading failure assumed to be caused by a signing problem?

If you're unsure, it can help to launch Archicad from Xcode and watch messages written by Archicad to the Console. Specifically, search for the names of the add-ons that fail to load in the console - Archicad is often more specific about by an add-on failed to load in that context.

Yes, you need to pay for Apple Developer membership if you want to sign add-ons.

I'm not aware of any blacklisting mechanism in Archicad.

I'm also not aware of any issue with loading add-ons in macOS 26.

[BFG]

Thank you for the previous response. I launched Archicad from Xcode as suggested and monitored the console output. While I did not find any explicit message about ExampleAddOn failing to load, I found this interesting error during startup:

cannot open file at line 51044 of [f0ca7bba1c]os_unix.c:51044: (2) open(/private/var/db/DetachedSignatures) - No such file or directory

The file /private/var/db/DetachedSignatures does not exist on my system. This appears to be a SQLite database that macOS uses for signature verification. Could this missing file be related to why Archicad is unable to validate and load our Add-On?

For reference, our Add-On is signed with an Apple Development certificate (Personal Team, free Apple ID), TeamIdentifier 696VQHZSKV, with flags=0x0(none) – no hardened runtime. All Add-Ons that load successfully in our installation are signed with TeamIdentifier 3E9E9FN277 (Graphisoft) with flags=0x10000(runtime).

Is there a supported workflow for loading locally developed Add-Ons without a paid Apple Developer membership, specifically on macOS 26 Tahoe?

[Akos Somorjai]

Hi BFG,

Please try to codesign the add-on with hardened runtime:

--timestamp --options runtime

Best, Akos

[BFG]

Update: Hardened runtime signing works but Gatekeeper still rejects

Following Akos' suggestion, I signed the Add-On with --timestamp --options runtime. The signature now shows flags=0x10000(runtime) and codesign --verify --deep --strict passes with no errors.

However, spctl --assess still rejects the bundle, and Archicad crashes during GS::ModuleFile::Load() → APIAddOn::CheckEnvironment() with a "Data Abort byte read Translation fault".

The issue appears to be that I'm using an Apple Development certificate (free Personal Team), not a Developer ID Application certificate (requires paid Apple Developer Program).

Questions:

1. Is a paid Apple Developer Program membership ($99/year) required to load Add-Ons locally during development?
2. Is there a way to test Add-Ons locally without notarization/Developer ID?
3. Could Archicad be launched in a "developer mode" that bypasses certificate validation for local Add-Ons?

[Ralph Wessel]

1. Yes, you need to pay for Apple Developer membership if you want to sign add-ons (for others to run).
2. I believe this will work if you select, "Sign to Run Locally"
3. I doubt it - this is managed by the OS

[BFG]

Hi again, Thanks for all the suggestions and replies, very grateful. I figured out what caused the problems

• The add-on didn't start up correctly — A setting in the code told the add-on to wait to be called upon by ArchiCAD, but ArchiCAD was waiting for the add-on to register itself first. They were waiting for each other and nothing happened.
• Wrong toolchain path during build — When building the add-on we used an incorrect path to the developer tools, which caused build errors.
• ArchiCAD crashed on load — As a result of the first issue, ArchiCAD attempted to load the add-on incorrectly, causing a crash. We identified the cause by reading crash reports from macOS.