Cannot connect to debugger

MAC OS Big Sur 11.3 ; XOJO 2020 Release 21; iOS app

I have an iOS app to which I’ve just made some small cosmetic changes. When I run in the simulator the app launches and immediately quits.

When I’m in the simulator and this happens, I tap the app icon and then get “"cannot connect to debugger"” message.

This app was working before updating the OSX and Xojo.
I have reset the simulator. I have checked to make sure that I have the relevant simulator installed, and this works with another app.

I’ have worked on this for a few days and no joy. I would appreciate any advice.

The debug log is too long to include.

Feb 6 05:57:18 Philips-MBP-2 bootlog[0]: BOOT_TIME 1612555038 318089
Feb 8 17:44:17 Philips-MBP-2 syslogd[14336]: Configuration Notice:
ASL Module “com.apple.family.asl” claims selected messages.
Those messages may not appear in standard system log files or in the ASL database.
Feb 8 17:44:17 Philips-MBP-2 syslogd[14336]: Configuration Notice:
ASL Module “com.apple.contacts.ContactsUICore” claims selected messages.
Those messages may not appear in standard system log files or in the ASL database.
Feb 8 17:44:17 Philips-MBP-2 syslogd[14336]: Configuration Notice:
ASL Module “com.apple.contacts.ContactsAutocomplete” claims selected messages.
Those messages may not appear in standard system log files or in the ASL database.
Feb 8 17:44:17 Philips-MBP-2 syslogd[14336]: Configuration Notice:
ASL Module “com.apple.clouddocs” claims selected messages.
Those messages may not appear in standard system log files or in the ASL database.
Feb 8 17:44:17 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.ids_simd): This service is defined to be constantly running and is inherently inefficient.
Feb 8 17:44:17 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.mediaartworkd): Unknown ProcessType: AdaptiveUtility
Feb 8 17:44:17 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.nanoregistryd): Unknown key for Boolean: TransactionTimeLimitEnabled
Feb 8 17:44:17 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.syslogd): Please switch away from OnDemand to KeepAlive.
Feb 8 17:44:17 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.xpc.launchd.domain.system): com.apple.mobiletimerd (lint): Invalid type for a LaunchEvent stream, should be a dictionary (stream/type): com.apple.alarm/bool
Feb 8 17:44:17 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.wcd): Unknown key for Boolean: TransactionTimeLimitEnabled
Feb 8 17:44:17 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.logd): Unknown key for Boolean: BeginTransactionAtShutdown
Feb 8 17:44:17 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.logd): This service is defined to be constantly running and is inherently inefficient.
Feb 8 17:44:17 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.backboardd): Unknown key for Boolean: HighPriorityIO
Feb 8 17:44:17 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.backboardd): This service is defined to be constantly running and is inherently inefficient.
Feb 8 17:44:17 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.managedconfiguration.profiled): ThrottleInterval set to zero. You’re not that important. Ignoring.
Feb 8 17:44:17 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.xpc.launchd.domain.system): com.apple.pluginkit.pkd (lint): Service sets EnableTransactions=false and EnablePressuredExit=true, which makes no sense. Enabling Transactions.
Feb 8 17:44:17 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.familycircled): Unknown key for dictionary: EnvironmentalVariables
Feb 8 17:44:17 Philips-MBP-2 syslogd[14336]: ASL Sender Statistics
Feb 8 17:44:17 Philips-MBP-2 diagnosticd[14366]: Posting stream filter: “{
global = 30064771081;
}”
Feb 8 17:44:17 Philips-MBP-2 diagnosticd[14366]: System mode client started - diagnosticd (14366) - mode: 0x9, filter: “”
Feb 8 17:44:17 Philips-MBP-2 diagnosticd[14366]: reflect channel created for fd 5
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLTimer is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7628) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101274680). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLIntersiloUniverse is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d5eb8) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101276200). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLIntersiloReplayService is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d6688) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x1012766b0). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLIntersiloRecordingProxyToRecipient is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d55a8) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x1012773d0). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLIntersiloRecordingProxyToInitiator is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d5648) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101277470). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLIntersiloRecordingProxy is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d5620) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101277448). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLSilo is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7538) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x1012787d0). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLDispatchTimerScheduler is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7588) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278820). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLDispatchSilo is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d75d8) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278870). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLIntersiloInterfaceSelectorInfo is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7678) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x1012788c0). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLIntersiloInterface is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d76c8) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278910). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLIntersiloProxyToRecipient is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7998) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278960). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLIntersiloProxyToInitiator is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7a38) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278a00). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLIntersiloProxy is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7a10) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x1012789d8). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLIntersiloService is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7ad8) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278a50). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLIntersiloServiceMock is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7b50) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278ac8). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLServiceVendorHeartbeatRecord is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7bc8) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278b40). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class _Locationd is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7c40) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278bb8). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class _CLMainService is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7c90) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278c08). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class _CLUnSupportedService is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7ce0) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278c58). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLServiceVendor is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7d08) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278c80). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLNotifierData is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7df8) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278d20). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLNotifierClientAdapter is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7e48) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278d70). One of the two will be used. Which one is undefined.
Feb 8 17:44:17 Philips-MBP-2 locationd[14355]: objc[14355]: Class CLNotifierServiceAdapter is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/CoreMotion.framework/CoreMotion (0x1015d7e98) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/locationd (0x101278e10). One of the two will be used. Which one is undefined.
Feb 8 17:44:18 Philips-MBP-2 securityd[14370]: objc[14370]: Class SOSCachedNotification is implemented in both /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/Security.framework/Security (0x110a80338) and /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 12.4.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/securityd (0x10f83d860). One of the two will be used. Which one is undefined.
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.AssetCacheLocatorService): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.AssetCacheLocatorService): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.MobileInstallationHelperService): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.MobileInstallationHelperService): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.Photos.CPLDiagnose): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.Photos.CPLDiagnose): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.StreamingUnzipService): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.StreamingUnzipService): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.UIKit.KeyboardManagement): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.UIKit.KeyboardManagement): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.accessibility.mediaaccessibilityd): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.accessibility.mediaaccessibilityd): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.accounts.dom): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.accounts.dom): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.backboard.display.archive): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.backboard.display.archive): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.datamigrator): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.datamigrator): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.imfoundation.IMRemoteURLConnectionAgent): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.imfoundation.IMRemoteURLConnectionAgent): Unknown key for integer: _DirtyJetsamMemoryLimit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.imfoundation.IMRemoteURLConnectionAgent): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.intents.intents-helper): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.intents.intents-helper): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.lsdiconservice): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.lsdiconservice): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.migrationpluginwrapper): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.migrationpluginwrapper): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.uifoundation-bundle-helper): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.uifoundation-bundle-helper): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.backboard.display.archive): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.backboard.display.archive): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.uifoundation-bundle-helper): Unknown key for Boolean: EnableTransactions
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.uifoundation-bundle-helper): Unknown key for Boolean: EnablePressuredExit
Feb 8 17:44:18 Philips-MBP-2 com.apple.CoreSimulator.SimDevice.3ED99B4B-DDB5-4D27-8C85-FCE3AEEC7FF2[14334] (com.apple.StreamingUnzipService): Unknown key for Boolean: EnableTransactions

I can only offer general advice. Upgrading both Xojo and Big Sur at the same time makes it hard to know which one could be having an issue. Plus Big Sur 11.3 is still in beta, and is a bit rough from what I’ve read.

I recommend trying one thing at a time to see if it can help pinpoint what is not working.

Thanks Paul,
Ihae a much older version of he same application, which runs OK. It ,just be something I have done in the process of updating the code. I am slowly working through it, but it is a slow and frustrating process.

In Xcode, you should have a crash log for the app.

Thanks
I tried to understand the crash log, but it didn’t help.
The problem was trying to set the view background colour using a method as follows:

(Cut and paste from somewhere I found a long time ago. If I don’t use this method, the code works. If I call it, I get the error message.)

So now I wonder - How. do I change the view background colour? The following code causes my app to crash.

Declare Function NSClassFromString Lib "Foundation" (className As CFStringRef) As Ptr
Declare Function colorWithRGBA Lib "UIKit" Selector "colorWithRed:green:blue:alpha:" ( UIColorClassRef As Ptr, red As CGFloat, green As CGFloat, blue As CGFloat, alpha As CGFloat) As Ptr
Declare Function view Lib "UIKit" Selector "view" (UIViewController As Ptr) As Ptr
Declare Sub setBackgroundColor Lib "UIKit" Selector "setBackgroundColor:" (UIView As Ptr, UIColor As Ptr)

Dim UIColorClassPtr As Ptr =  NSClassFromString("UIColor")
Dim colorPtr As ptr = colorWithRGBA(UIColorClassPtr, (255 / 255), (251 / 255), (230 / 255), 1)
Dim viewPtr As Ptr = view(v.Handle) //only change here
setBackgroundColor(viewPtr, colorPtr)

So in your case, what is v?

Thanks Greg,
Excellent point.I have obviously stuffed up with the calling routine. I am now doing my best to understand the original code and work out where I have gone wrong.