Update: Ok, the original problem was missing entitlements. Now it fails with: default Finder +[NSExtensionContext _allowedItemPayloadClasses] not implemented. Setting the allowed payload classes to <private> default macmount-actions +[NSExtensionContext _allowedItemPayloadClasses] not implemented. Setting the allowed payload classes to <private> error cfprefsd Couldn't open parent path due to [2: No such file or directory] default macmount-actions NSApp cache appearance: -NSRequiresAquaSystemAppearance: 0 -appearance: (null) -effectiveAppearance: <NSCompositeAppearance: 0x14760ce80 ( "<NSAquaAppearance: 0x150811e30>", "<NSSystemAppearance: 0x15080cc90>" )> default distnoted register name: com.apple.nsquiet_safe_quit_give_reason object: com.mycompany.macmount-actions token: 3b0000003b pid: 52332 default macmount-actions *** Assertion failure in -[FPUIActionExtensionContainerViewController _configureWithDomainIdentifier:], FPUIActionExtensionContainerViewController.m:129 error Finder Action with identifier (<private>) did finish with error (Error Domain=com.apple.ViewBridge Code=14 UserInfo={com.apple.ViewBridge.error.hint=<private>, com.apple.ViewBridge.error.description=NSViewBridgeErrorServiceBootstrap}). error Finder FP Custom action sheet finished with error Error Domain=com.apple.ViewBridge Code=14 "(null)" UserInfo={com.apple.ViewBridge.error.hint=-[NSViewServiceMarshal bootstrap:withReply:] caught NSInternalInconsistencyException 'attempting to send message to non-existent action extension view controller' with backtrace ( "0 CoreFoundation __exceptionPreprocess + 176", "1 libobjc.A.dylib objc_exception_throw + 60", "2 Foundation -[NSCalendarDate initWithCoder:] + 0", "3 FileProviderUI -[FPUIActionExtensionContainerViewController _configureWithDomainIdentifier:] + 164", "4 FileProviderUI -[FPUIActionExtensionContainerViewController awakeFromRemoteView] + 692", "5 ViewBridge -[NSViewServiceMarshal _bootstrap:replyData:completion:] + 1828", "6 ViewBridge -[NSViewServiceMarshal bootstrap:withReply:] + 272", "7 CoreFoundation __invoking___ + 148", "8 CoreFoundation -[NSInvocation invoke] + 428", "9 CoreFoundation -[NSInvocation invokeWithTarget:] + 64", "10 ViewBridge -[NSVB_ViewServiceImplicitAnimationDecodingProxy forwardInvocation:] + 192", "11 CoreFoundation ___forwarding___ + 976", "12 CoreFoundation _CF_forwarding_prep_0 + 96", "13 CoreFoundation __invoking___ + 148", "14 CoreFoundation -[NSInvocation invoke] + 428", "15 CoreFoundation -[NSInvocation invokeWithTarget:] + 64", "16 ViewBridge -[NSVB_QueueingProxy forwardInvocation:] + 300", "17 CoreFoundation ___forwarding___ + 976", "18 CoreFoundation _CF_forwarding_prep_0 + 96", "19 CoreFoundation __invoking___ + 148", "20 CoreFoundation -[NSInvocation invoke] + 428", "21 CoreFoundation -[NSInvocation invokeWithTarget:] + 64", "22 CoreFoundation ___forwarding___ + 976", "23 CoreFoundation _CF_forwarding_prep_0 + 96", "24 CoreFoundation __invoking___ + 148", "25 CoreFoundation -[NSInvocation invoke] + 428", "26 ViewBridge __deferNSXPCInvocationOntoMainThread_block_invoke + 120", "27 ViewBridge __wrapBlockWithVoucher_block_invoke + 56", "28 ViewBridge kNotRunningOnAppKitCompatibleThread_block_invoke + 360", "29 CoreFoundation __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 28", "30 CoreFoundation __CFRunLoopDoBlocks + 364", "31 CoreFoundation __CFRunLoopRun + 2432", "32 CoreFoundation CFRunLoopRunSpecific + 612", "33 HIToolbox RunCurrentEventLoopInMode + 292", "34 HIToolbox ReceiveNextEventCommon + 648", "35 HIToolbox _BlockUntilNextEventMatchingListInModeWithFilter + 76", "36 AppKit _DPSNextEvent + 636", "37 AppKit -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 716", "38 ViewBridge __77-[NSViewServiceApplication vbNextEventMatchingMask:untilDate:inMode:dequeue:]_block_invoke + 136", "39 ViewBridge -[NSViewServiceApplication _withToxicEventMonitorPerform:] + 152", "40 ViewBridge -[NSViewServiceApplication vbNextEventMatchingMask:untilDate:inMode:dequeue:] + 168", "41 ViewBridge -[NSViewServiceApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 100", "42 AppKit -[NSApplication run] + 464", "43 AppKit NSApplicationMain + 880", "44 libxpc.dylib _xpc_objc_main + 976", "45 libxpc.dylib xpc_main + 108", "46 Foundation +[NSXPCListener serviceListener] + 0", "47 PlugInKit pkSafeDataFromRelativeURL + 33800", "48 PlugInKit pkSafeDataFromRelativeURL + 32752", "49 PlugInKit pkSafeDataFromRelativeURL + 34680", "50 ExtensionFoundation EXExtensionMain + 268", "51 Foundation NSExtensionMain + 204", "52 dyld start + 2236" ), com.apple.ViewBridge.error.description=NSViewBridgeErrorServiceBootstrap} error 23:24:30.455372+0900 Finder FP Custom action sheet failed to load with error Error Domain=com.apple.ViewBridge Code=14 "(null)" UserInfo={com.apple.ViewBridge.error.hint=-[NSViewServiceMarshal bootstrap:withReply:] caught NSInternalInconsistencyException 'attempting to send message to non-existent action extension view controller' with backtrace ( <same backtrace as above>), com.apple.ViewBridge.error.description=NSViewBridgeErrorServiceBootstrap}

I mean, I'm submitting an .ipa to appstoreconnect via regular app GUI ("Distribute App..." in Xcode Organizer, "Deliver" in Transporter). Interesting enough, Application Loader worked fine.

Same happens for me with both xcode and transporter (manually initiated submission to appstoreconnect) with 99% failure rate.