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App Center Crashes (macOS)

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Important

Visual Studio App Center is scheduled for retirement on March 31, 2025. While you can continue to use Visual Studio App Center until it is fully retired, there are several recommended alternatives that you may consider migrating to.

Learn more about support timelines and alternatives.

App Center Crashes will automatically generate a crash log every time your app crashes. The log is first written to the device's storage and when the user starts the app again, the crash report will be sent to App Center. Collecting crashes works for both beta and live apps, i.e. those submitted to the App Store. Crash logs contain valuable information for you to help fix the crash.

Follow the Getting Started section if you haven't set up the SDK in your application yet.

Also, crash logs on macOS require Symbolication, check out the App Center Diagnostics documentation that explains how to provide symbols for your app.

Note

In the 4.0.0 version of App Center breaking changes were introduced. Follow the Migrate to App Center SDK 4.0.0 and higher section to migrate App Center from previous versions.

Crash reporting in extensions

App Center supports crash reporting in macOS extensions. The usage is the same as in the container application.

Generate a test crash

App Center Crashes provides you with an API to generate a test crash for easy testing of the SDK. This API can only be used in test/beta apps and won't do anything in production apps.

[MSACCrashes generateTestCrash];

Crashes.generateTestCrash()

Get more information about a previous crash

App Center Crashes has two APIs that give you more information in case your app has crashed.

Did the app receive a low memory warning in the previous session?

At any time after starting the SDK, you can check if the app received a memory warning in the previous session:

[MSACCrashes hasReceivedMemoryWarningInLastSession];

Crashes.hasReceivedMemoryWarningInLastSession

Note

This method must only be used after Crashes has been started, it will always return NO or false before start.

Note

In some cases, a device with low memory can't send events.

Did the app crash in the previous session?

At any time after starting the SDK, you can check if the app crashed in the previous launch:

[MSACCrashes hasCrashedInLastSession];

Crashes.hasCrashedInLastSession

This comes in handy in case you want to adjust the behavior or UI of your app after a crash has occurred.

Note

This method must only be used after MSACCrashes has been started, it will always return NO or false before start.

Details about the last crash

If your app crashed previously, you can get details about the last crash.

MSACErrorReport *crashReport = [MSACCrashes lastSessionCrashReport];

var crashReport = Crashes.lastSessionCrashReport

Note

This method must only be used after Crashes has been started, it will always return nil before start.

There are numerous use cases for this API, the most common one is people who call this API and implement their custom CrashesDelegate.

Customize your usage of App Center Crashes

App Center Crashes provides callbacks for developers to perform additional actions before and when sending crash logs to App Center.

To add your custom behavior, you need to adopt the CrashesDelegate-protocol, all of its methods are optional.

Register as a delegate

[MSACCrashes setDelegate:self];

Crashes.delegate = self

Note

You must set the delegate before calling AppCenter.start, since App Center starts processing crashes immediately after the start.

Should the crash be processed?

Implement the crashes:shouldProcessErrorReport:-method in the class that adopts the CrashesDelegate-protocol if you want to decide if a particular crash needs to be processed or not. For example, there could be a system level crash that you'd want to ignore and that you don't want to send to App Center.

- (BOOL)crashes:(MSACCrashes *)crashes shouldProcessErrorReport:(MSACErrorReport *)errorReport {
  return YES; // return YES if the crash report should be processed, otherwise NO.
}

func crashes(_ crashes: Crashes, shouldProcess errorReport: ErrorReport) -> Bool {
  return true; // return true if the crash report should be processed, otherwise false.
}

Handled Errors

App Center also allows you to track errors by using handled exceptions via trackError method. An app can optionally attach properties or/and attachments to a handled error report to provide further context.

@try {
  // Throw error.
} @catch (NSError *error) {

  // Init attachments.
  NSArray<MSACErrorAttachmentLog *> attachments = @[ MSACErrorAttachmentLog attachmentWithText:@"Hello world!" filename:@"hello.txt"] ]

  // Init properties.
  NSDictionary *properties = @{ "Category" : "Music", "Wifi" : "On" };

  // Track errors.
  [MSACCrashes trackError:error withProperties:properties attachments:attachments];
  [MSACCrashes trackError:error withProperties:properties attachments:nil];
  [MSACCrashes trackError:error withProperties:nil attachments:attachments];
  [MSACCrashes trackError:error withProperties:nil attachments:nil];
}

do {
  // Throw error.
} catch {

  // Init attachments.
  let attachments = [ErrorAttachmentLog.attachment(withText: "Hello world!", filename: "hello.txt")]

  // Init properties.
  let properties:Dictionary<String, String> = ["Category" : "Music", "Wifi" : "On"]

  // Track errors.
  Crashes.trackError(error, properties: properties, attachments: attachments)
  Crashes.trackError(error, properties: properties, attachments: nil)
  Crashes.trackError(error, properties: nil, attachments: attachments)
  Crashes.trackError(error, properties: nil, attachments: nil)
}

For track exceptions you can use trackException method:

@try {
  // Throw exceptions.
} @catch (NSException *exception) {

  // Init exceptions.
  MSACExceptionModel *customException1 = [MSACExceptionModel initWithType:@"Custom exception" exceptionMessage:"Track custom exception.", stackTrace:exception.callStackSymbols];
  MSACExceptionModel *customException2 = [MSACExceptionModel initWithException:exception];

  // Track exceptions.
  [MSACCrashes trackException:customException1 withProperties:properties attachments:nil];
  [MSACCrashes trackException:customException2 withProperties:properties attachments:nil];
}

do {
  // Throw exception.
} catch {

  // Init exception.
  let exception = ExceptionModel(withType: "Custom exception", exceptionMessage: "Track custom exception.", stackTrace: Thread.callStackSymbols)

  // Track exception.
  Crashes.trackException(exception, properties: properties, attachments: nil)
}

If user privacy is important to you, you might want to get user confirmation before sending a crash report to App Center. The SDK exposes a callback that tells App Center Crashes to await user confirmation before sending any crash reports.

If you chose to do so, you're responsible for obtaining the user's confirmation, e.g. through a dialog prompt with one of the following options: Always send, Send, and Don't send. Based on the input, you'll tell App Center Crashes what to do and the crash will then be handled accordingly.

Note

The SDK doesn't display a dialog for this, the app must provide its own UI to ask for user consent.

The following method shows how to set up a user confirmation handler:

[MSACCrashes setUserConfirmationHandler:(^(NSArray<MSACErrorReport *> *errorReports) {

  // Your code to present your UI to the user, e.g. an NSAlert.
  NSAlert *alert = [[NSAlert alloc] init];
  [alert setMessageText:@"Sorry about that!"];
  [alert setInformativeText:@"Do you want to send an anonymous crash report so we can fix the issue?"];
  [alert addButtonWithTitle:@"Always send"];
  [alert addButtonWithTitle:@"Send"];
  [alert addButtonWithTitle:@"Don't send"];
  [alert setAlertStyle:NSWarningAlertStyle];

  switch ([alert runModal]) {
  case NSAlertFirstButtonReturn:
    [MSACCrashes notifyWithUserConfirmation:MSACUserConfirmationAlways];
    break;
  case NSAlertSecondButtonReturn:
    [MSACCrashes notifyWithUserConfirmation:MSACUserConfirmationSend];
    break;
  case NSAlertThirdButtonReturn:
    [MSACCrashes notifyWithUserConfirmation:MSACUserConfirmationDontSend];
    break;
  default:
    break;
  }

  return YES; // Return YES if the SDK should await user confirmation, otherwise NO.
})];

Crashes.setUserConfirmationHandler({ (errorReports: [ErrorReport]) in

  // Your code to present your UI to the user, e.g. an NSAlert.
  let alert: NSAlert = NSAlert()
  alert.messageText = "Sorry about that!"
  alert.informativeText = "Do you want to send an anonymous crash report so we can fix the issue?"
  alert.addButton(withTitle: "Always send")
  alert.addButton(withTitle: "Send")
  alert.addButton(withTitle: "Don't send")
  alert.alertStyle = NSWarningAlertStyle

  switch (alert.runModal()) {
  case NSAlertFirstButtonReturn:
    Crashes.notify(with: .always)
    break;
  case NSAlertSecondButtonReturn:
    Crashes.notify(with: .send)
    break;
  case NSAlertThirdButtonReturn:
    Crashes.notify(with: .dontSend)
    break;
  default:
    break;
  }

  return true // Return true if the SDK should await user confirmation, otherwise return false.
})

In case you return YES/true in the handler block above, your app should obtain user permission and message the SDK with the result using the following API. If you're using an alert for this, as we do in the sample above, you'd call it based on the result (ModalResponse) of runModal call.

// Depending on the user's choice, call notifyWithUserConfirmation: with the right value.
[MSACCrashes notifyWithUserConfirmation:MSACUserConfirmationDontSend];
[MSACCrashes notifyWithUserConfirmation:MSACUserConfirmationSend];
[MSACCrashes notifyWithUserConfirmation:MSACUserConfirmationAlways];

// Depending on the user's choice, call notify(with:) with the right value.
Crashes.notify(with: .dontSend)
Crashes.notify(with: .send)
Crashes.notify(with: .always)

Enable catching uncaught exceptions thrown on the main thread

AppKit catches exceptions thrown on the main thread, preventing the application from crashing on macOS, so the SDK can't catch these crashes. To mimic iOS behavior, set NSApplicationCrashOnExceptions flag before SDK initialization, this flag allows the application to crash on uncaught exceptions and the SDK can report them.

[[NSUserDefaults standardUserDefaults] registerDefaults:@{ @"NSApplicationCrashOnExceptions" : @YES }];

UserDefaults.standard.register(defaults: ["NSApplicationCrashOnExceptions": true])

Note

App Center SDK set the flag automatically in versions 1.10.0 and below. Starting with version 1.11.0 this flag is no longer set automatically.

Disable forwarding of the application main class's methods calls to App Center Crashes

The App Center Crashes SDK uses swizzling to improve its integration by forwarding itself some of the application main class's methods calls. Method swizzling is a way to change the implementation of methods at runtime. If for any reason you don't want to use swizzling (e.g. because of a specific policy), you should override the application's reportException: and sendEvent: methods yourself in order for Crashes to report exceptions thrown on the main thread correctly.

  1. Create ReportExceptionApplication.m file and add the following implementation:

    @import Cocoa;
@import AppCenterCrashes;

@interface ReportExceptionApplication : NSApplication
@end

@implementation ReportExceptionApplication

- (void)reportException:(NSException *)exception {
  [MSACCrashes applicationDidReportException:exception];
  [super reportException:exception];
}

- (void)sendEvent:(NSEvent *)theEvent {
  @try {
    [super sendEvent:theEvent];
  } @catch (NSException *exception) {
    [self reportException:exception];
  }
}

@end

    Note

    Swift's try/catch doesn't work with NSException. These exceptions can be handled in Objective-C only.

  2. Open Info.plist file and replace the NSApplication in the Principal class field with your application class name, ReportExceptionApplication in this example.

  3. To disable swizzling in App Center SDK, add the AppCenterApplicationForwarderEnabled key to Info.plist file, and set the value to 0.

Get information about the sending status for a crash log

At times, you want to know the status of your app crash. A common use case is that you might want to show UI that tells the users that your app is submitting a crash report, or, in case your app is crashing quickly after the launch, you want to adjust the behavior of the app to make sure the crash logs can be submitted. The CrashesDelegate-protocol defines three different callbacks that you can use in your app to be notified of what's going on:

The following callback will be invoked before the SDK sends a crash log

- (void)crashes:(MSACCrashes *)crashes willSendErrorReport:(MSACErrorReport *)errorReport {
  // Your code, e.g. to present a custom UI.
}

func crashes(_ crashes: Crashes, willSend errorReport: ErrorReport) {
  // Your code, e.g. to present a custom UI.
}

In case we have network issues or an outage on the endpoint, and you restart the app, willSendErrorReport is triggered again after process restart.

The following callback will be invoked after the SDK sent a crash log successfully

- (void)crashes:(MSACCrashes *)crashes didSucceedSendingErrorReport:(MSACErrorReport *)errorReport {
  // Your code, e.g. to hide the custom UI.
}

func crashes(_ crashes: Crashes, didSucceedSending errorReport: ErrorReport) {
  // Your code goes here.
}

The following callback will be invoked if the SDK failed to send a crash log

- (void)crashes:(MSACCrashes *)crashes didFailSendingErrorReport:(MSACErrorReport *)errorReport withError:(NSError *)error {
  // Your code goes here.
}

func crashes(_ crashes: Crashes, didFailSending errorReport: ErrorReport, withError error: Error) {
  // Your code goes here.
}

Receiving didFailSendingErrorReport means a non-recoverable error such as a 4xx code occurred. For example, 401 means the appSecret is wrong.

This callback isn't triggered if it's a network issue. In this case, the SDK keeps retrying (and also pauses retries while the network connection is down).

Add attachments to a crash report

You can add binary and text attachments to a crash report. The SDK will send them along with the crash so that you can see them in App Center portal. The following callback will be invoked right before sending the stored crash from previous application launches. It won't be invoked when the crash happens. Here is an example of how to attach text and an image to a crash:

- (NSArray<MSACErrorAttachmentLog *> *)attachmentsWithCrashes:(MSACCrashes *)crashes
                                             forErrorReport:(MSACErrorReport *)errorReport {
  MSACErrorAttachmentLog *attachment1 = [MSACErrorAttachmentLog attachmentWithText:@"Hello world!" filename:@"hello.txt"];
  MSACErrorAttachmentLog *attachment2 = [MSACErrorAttachmentLog attachmentWithBinary:[@"Fake image" dataUsingEncoding:NSUTF8StringEncoding] filename:@"fake_image.jpeg" contentType:@"image/jpeg"];
  return @[ attachment1, attachment2 ];
}

func attachments(with crashes: Crashes, for errorReport: ErrorReport) -> [ErrorAttachmentLog]? {
  let attachment1 = ErrorAttachmentLog.attachment(withText: "Hello world!", filename: "hello.txt")
  let attachment2 = ErrorAttachmentLog.attachment(withBinary: "Fake image".data(using: String.Encoding.utf8), filename: nil, contentType: "image/jpeg")
  return [attachment1!, attachment2!]
}

Note

The size limit is currently 7 MB. Attempting to send a larger attachment will trigger an error.

Enable or disable App Center Crashes at runtime

You can enable and disable App Center Crashes at runtime. If you disable it, the SDK won't do any crash reporting for the app.

[MSACCrashes setEnabled:NO];

Crashes.enabled = false

To enable App Center Crashes again, use the same API but pass YES/true as a parameter.

[MSACCrashes setEnabled:YES];

Crashes.enabled = true

The state is persisted in the device's storage across application launches.

Note

This method must only be used after Crashes has been started.

Check if App Center Crashes is enabled

You can also check if App Center Crashes is enabled or not:

BOOL enabled = [MSACCrashes isEnabled];

var enabled = Crashes.enabled

Note

This method must only be used after Crashes has been started, it will always return false before start.

Disabling Mach exception handling

By default, App Center Crashes uses the Mach exception handler to catch fatal signals, e.g. stack overflows, via a Mach exception server.

The disableMachExceptionHandler-method provides an option to disable catching fatal signals via a Mach exception server. If you want to disable the Mach exception handler, you should call this method BEFORE starting the SDK. Your typical setup code would look like this:

[MSACCrashes disableMachExceptionHandler];
[MSACAppCenter start:@"{Your App Secret}" withServices:@[[MSACAnalytics class], [MSACCrashes class]]];

Crashes.disableMachExceptionHandler()
AppCenter.start(withAppSecret: "{Your App Secret}", services: [Analytics.self, Crashes.self])