SIGABRT Error (Signal Abort)

SIGABRT means the app was forcefully terminated because it encountered a serious runtime issue.

On Apple platforms, it commonly appears as:

text id=”m7q2we”
Thread 1: signal SIGABRT

This is one of the most common iOS/macOS crash types.

Common causes in iOS (Objective-C / Swift)

1. Array out of bounds

objectivec id=”v4k8ra”
NSArray *arr = @[@”A”];
NSLog(@”%@”, arr[5]);

Fix

objectivec id=”n3p1xd”
if (index < arr.count) {
NSLog(@”%@”, arr[index]);
}

2. Unrecognized selector

Calling a method that object doesn’t support.

objectivec id=”u8w5kc”
[idString addObject:@”Test”];

Crash:

text id=”g7q2mv”
unrecognized selector sent to instance

3. IBOutlet not connected

Very common in Xcode Storyboards/XIBs.

Example:

objectivec id=”r4k9zn”
self.titleLabel.text = @”Hello”;

but titleLabel is disconnected or nil.

4. AutoLayout constraint conflict

Conflicting UI constraints may trigger:

text id=”t2p5xe”
Unable to simultaneously satisfy constraints

5. Force unwrap crash (Swift)

swift id=”q6m3yt”
let name: String! = nil
print(name)

6. Core Data crash

Using invalid managed objects/context.

7. JSON parsing issue

objectivec id=”w9k1vc”
NSDictionary *dict = json[@”data”];

when response is actually an array.

8. Main thread violations

Updating UI from background thread.

Wrong

objectivec id=”p4q7ra”
dispatch_async(dispatch_get_global_queue(0,0), ^{
self.label.text = @”Test”;
});

Correct

objectivec id=”j8m2kd”
dispatch_async(dispatch_get_main_queue(), ^{
self.label.text = @”Test”;
});

How to identify exact SIGABRT cause

In Xcode

Open:

• Debug Navigator
• Console
• Stack Trace

The real reason is usually a few lines above SIGABRT.

Look for messages like:

text id=”x5q7ne”
Terminating app due to uncaught exception

Examples:

text id=”f3k1wc”
NSInvalidArgumentException

text id=”b7p4xd”
index 5 beyond bounds

Debugging tips

Enable Exception Breakpoint

In Xcode:

1. Breakpoint Navigator
2. Click +
3. Add Exception Breakpoint

This stops exactly where crash occurs.

Common SIGABRT-related exceptions

| Exception | Meaning |
| – | |
| NSInvalidArgumentException | Wrong method/object |
| NSRangeException | Array index issue |
| EXC_BAD_ACCESS | Invalid memory access |
| NSUnknownKeyException | Broken IBOutlet |
| fatal error | Swift runtime issue |

Firebase Crash Reporting

Useful tools:

• Firebase Crashlytics
• Apple Developer Documentation

Most important

SIGABRT itself is not the root cause.
The real issue is usually:

• exception,
• invalid object,
• storyboard connection,
• array access,
• or threading issue.

The actual reason appears above the SIGABRT line in logs.