Debugging auv3; where/what is AUv3instance.mm?

I’m debugging my auv3 within a host,Ableton Live in this case. had to use csrutil disable for that…
I’d like to know how to proceed: I get a hint about AUv3Instance.mm:1385 but I can not find that file, and therefore also not look up what is being called etc. etc.
After repeated complaints about an invalid property it quits.
My parameter ID all are big numbers, and I dont know what “property IDs” are…
property IDs 15 and 16 are noted to be false, I truncated the debug info here.
Thanks in advance!

2023-09-27 10:58:16.566090+0200 Space Guitar[2104:50365]
 [subsystems] Bootstrapping; external subsystem UIKit_PKSubsystem refused setup

2023-09-27 10:58:16.945201+0200 Live[2089:49778] [audiocomp]   
        AUv3Instance.mm:1385  
Invalid property id 15 (scope 1, element 0, size 16)

After the first scope 0, id15 error,
3 errors come from scope 0: these are parameter ID’s however

2023-09-27 10:58:17.112587+0200 Live[2089:49778] [audiocomp] AUv3Instance.mm:890 Invalid property id 16 (scope 0, element 1685069138)

I got 3 parameters with this Invalid property id 16
the parameters where found OK in auval

That’s not a JUCE file; I assume it’s the name of a source file in Live itself.

“Property ID” might be referring to the AudioUnitPropertyID enum found in AudioUnitProperties.h (an Apple system header). ID 15 is kAudioUnitProperty_SetExternalBuffer, and 16 is kAudioUnitProperty_ParameterValueStrings.

You may be able to attach a debugger to the AUv3 plugin itself, which runs in a separate process to Live. This will give you more information about what’s happening before Live quits. It’s possible that the logging you’re seeing is just warning you about potential unwanted behaviour, but the plugin is failing for unrelated reasons. Alternatively, it might be that the plugin is doing everything correctly, but some edge case isn’t handled correctly on Live’s side.

ok, thanks for the pointers here!
… I know virtually nothing about AUv3. I’ve got an error free reliable iOS auv3 app, but behaviour on macOS is different.
I allready am debugging the AUv3 in host. When I know where the error occurs I can set some breakpoints and see what is going awry.
In my processor a 10fps gesture is done to 3 parameters in the tree, with gently fail, that is: if the processor can’t get the lock, it will not update. These are sliders that can be switched between manual and envelop mode.
This works fine in iOS, but I now suspect that this causes the problem: what I did there is not standard, so the chance of unknown quirks is maximal.
I’ll just disable the gestures in the processor and see where this leads me…