I took code-level support from Apple and they told me that this is a known issue in iOS, and the only workaround is for the user to reboot the device. "The problem you are encountering is due to a currently known issue in iOS, where in some cases, after an app update, the Notification Extension fails to launch. At this time, the only workaround to this is to reboot the device, after which the extension will be launched as expected. The time frame for a fix is not known at this time. We will invite you to file a bug report about this to increase the visibility of the issue, and help the team adequately prioritize a solution. In the bug report please explain the impact on your customers and an approximate number of customers that are being affected. Also include all the logging information you have about it. You can file your report at https://developer.apple.com/bug-reporting" Hopefully, this helps someone save a day's worth of time investigating this issue.

Console.log default 11:55:38.178328-0500 SpringBoard [com.company.product] Received remote notification request <request_id> [ waking: 0, hasAlertContent: 1, hasSound: 0 hasBadge: 0 hasContentAvailable: 0 hasMutableContent: 1 pushType: Alert] default 11:55:38.178386-0500 SpringBoard [com.company.product] Remote notification request <request_id> can be modified: 1 default 11:55:38.183924-0500 pkd Mapped bundleID com.company.product to personal: PKDPersona: personaID: 1000, isEnterprise: NO default 11:55:38.186093-0500 runningboardd Executing launch request for xpcservice<com.company.product.yyyyy([osservice<com.apple.SpringBoard>:33])> (Launching extension com.company.product.yyyyy(134589AC-5665-4423-B56D-46F8C8DB18CA) for host 33) default 11:55:38.186208-0500 runningboardd Skipping preflight as <RBSLaunchRequest| xpcservice<com.company.product.yyyyy([osservice<com.apple.SpringBoard>:33])>; "Launching extension com.company.product.yyyyy(134589AC-5665-4423-B56D-46F8C8DB18CA) for host 33"> is not an app default 11:55:38.186271-0500 runningboardd Creating and launching job for: xpcservice<com.company.product.yyyyy([osservice<com.apple.SpringBoard>:33])> default 11:55:38.186691-0500 runningboardd '(null)' Submitting extension overlay (host PID 33, path /private/var/containers/Bundle/Application/<app_id>/appname.app/PlugIns/nse.appex/nse): <dictionary: 0xaf4a6d870> { count = 4, transaction: 0, voucher = 0x0, contents = "_AdditionalProperties" => <dictionary: 0xaf4ae22c0> { count = 1, transaction: 0, voucher = 0x0, contents = "RunningBoard" => <dictionary: 0xaf4ae6f30> { count = 3, transaction: 0, voucher = 0x0, contents = "Managed" => <bool: 0x262f9c9e0>: true "RunningBoardLaunchedIdentity" => <dictionary: 0xaf4aed8c0> { count = 4, transaction: 0, voucher = 0x0, contents = "TYPE" => <int64: 0x87ebed049aadc05f>: 4 "h" => <int64: 0x87ebed049aadc177>: 33 "i" => <string: 0xaf4afd320> { length = 33, contents = "com.company.product.yyyyy" } "r" => <int64: 0x87ebed049aadc06f>: 2 } "RunningBoardLaunched" => <bool: 0x262f9c9e0>: true } } "XPCService" => <dictionary: 0xaf4a23830> { count = 8, transaction: 0, voucher = 0x0, contents = "Platform" => <int64: 0x87ebed049aadc06f>: 2 "RunLoopType" => <string: 0xaf4a26470> { length = 9, contents = "NSRunLoop" } "_SandboxProfile" => <string: 0xaf4ae2620> { length = 10, contents = "silent-nse" } "_AdditionalSubServices" => <dictionary: 0xaf4a66530> { count = 1, transaction: 0, voucher = 0x0, contents = "apple-extension-service" => <bool: 0x262f9c9e0>: true } "PersonaEnterprise" => <int64: 0x87ebed049aaddf3f>: 1000 "EnvironmentVariables" => <dictionary: 0xaf4aef6d0> { count = 3, transaction: 0, voucher = 0x0, contents = "TMPDIR" => <string: 0xaf4a604b0> { length = 92, contents = "/private/var/mobile/Containers/Data/PluginKitPlugin/<plugin_id>/tmp" } "HOME" => <string: 0xaf4a713e0> { length = 88, contents = "/private/var/mobile/Containers/Data/PluginKitPlugin/<plugin_id>" } "CFFIXED_USER_HOME" => <string: 0xaf4a5e790> { length = 88, contents = "/private/var/mobile/Containers/Data/PluginKitPlugin/<plugin_id>" } } "_OmitSandboxParameters" => <bool: 0x262f9c9e0>: true "ProgramArguments" => <array: 0xaf4aac460> { count = 3, capacity = 8, contents = 0: <string: 0xaf4abd760> { length = 149, contents = "/private/var/containers/Bundle/Application/<app_id>/appname.app/PlugIns/nse.appex/nse" } 1: <string: 0xaf4aa90e0> { length = 15, contents = "-AppleLanguages" } 2: <string: 0xaf4aa1f20> { length = 9, contents = "("en-GB")" } } } "RunningBoard" => <dictionary: 0xaf4ae6f30> { count = 3, transaction: 0, voucher = 0x0, contents = "Managed" => <bool: 0x262f9c9e0>: true "RunningBoardLaunchedIdentity" => <dictionary: 0xaf4aed8c0> { count = 4, transaction: 0, voucher = 0x0, contents = "TYPE" => <int64: 0x87ebed049aadc05f>: 4 "h" => <int64: 0x87ebed049aadc177>: 33 "i" => <string: 0xaf4afd320> { length = 33, contents = "com.company.product.yyyyy" } "r" => <int64: 0x87ebed049aadc06f>: 2 } "RunningBoardLaunched" => <bool: 0x262f9c9e0>: true } "CFBundlePackageType" => <string: 0xaf4a73b30> { length = 4, contents = "XPC!" } } error 11:55:38.195184-0500 SpringBoard [u 134589AC-5665-4423-B56D-46F8C8DB18CA:m (null)] [<private>(<private>)] Failed to start plugin; pkd returned an error: Error Domain=PlugInKit Code=4 "RBSLaunchRequest error trying to launch plugin com.company.product.yyyyy(134589AC-5665-4423-B56D-46F8C8DB18CA): Error Domain=RBSRequestErrorDomain Code=5 "Launch failed." UserInfo={NSLocalizedFailureReason=Launch failed., NSUnderlyingError=0x770bc46b0 {Error Domain=NSPOSIXErrorDomain Code=111 "Unknown error: 111" UserInfo={NSLocalizedDescription=Launchd job spawn failed}}}" UserInfo={NSLocalizedDescription=RBSLaunchRequest error trying to launch plugin com.company.product.yyyyy(134589AC-5665-4423-B56D-46F8C8DB18CA): Error Domain=RBSRequestErrorDomain Code=5 "Launch failed." UserInfo={NSLocalizedFailureReason=Launch failed., NSUnderlyingError=0x770bc46b0 {Error Domain=NSPOSIXErrorDomain Code=111 "Unknown error: 111" UserInfo={NSLocalizedDescription=Launchd job spawn failed}}}} error 11:55:38.195359-0500 SpringBoard Plugin <id<PKPlugIn>: 0xa0ce884a0; core = <[u 134589AC-5665-4423-B56D-46F8C8DB18CA] [com.company.product.yyyyy(version)],[d CC34D016-FF8A-4917-AB20-6F9BD00D97FE] [/private/var/containers/Bundle/Application/<app_id>/appname.app/PlugIns/nse.appex]>, instance = [(null)], state = 3, useCount = 0> must have pid! Extension request will fail error 11:55:38.195425-0500 SpringBoard Failed to acquire assertion for plugin: <id<PKPlugIn>: 0xa0ce884a0; core = <[u 134589AC-5665-4423-B56D-46F8C8DB18CA] [com.company.product.yyyyy(version)],[d CC34D016-FF8A-4917-AB20-6F9BD00D97FE] [/private/var/containers/Bundle/Application/<app_id>/appname.app/PlugIns/nse.appex]>, instance = [(null)], state = 3, useCount = 0> pid: 0