Crash: NSInvalidArgumentException in OSMessagingController during In-App Messaging fetch (attemptFetchWithRetries)

[dipak-dr-iOS]

What happened?

Our app is experiencing a runtime crash inside the OneSignal iOS SDK when the SDK attempts to fetch In-App Messages.

The crash consistently happens inside:

OSMessagingController → attemptFetchWithRetries:rywData:
OneSignalClient → handleJSONNSURLResponse:data:error:

The exception thrown is:

NSInvalidArgumentException
+[NSObject(NSObject) _copyDescription]
unrecognized selector sent to instance

Based on investigation, the SDK is receiving an unexpected JSON value (likely NSNull or wrong type) in the IAM fetch response. The SDK then calls _copyDescription on that value during retry handling, which causes a fatal crash.

This is happening in production and is completely outside of our app logic. It appears to be a type-safety bug in the OneSignal SDK.

Steps to reproduce?

1. Integrate OneSignal SDK into an iOS app (In-App Messaging enabled).
2. Launch the app on a real device.
3. Allow OneSignal to attempt an IAM fetch from the server.
4. When the server returns a malformed or null IAM field during retry handling,
   the SDK crashes with NSInvalidArgumentException.
5. Crash appears to originate from passing NSNull / invalid object to _copyDescription.

What did you expect to happen?

The OneSignal SDK should safely handle unexpected or null JSON values in the IAM response.
Malformed fields (such as null, empty dictionary, or wrong type) should not cause the SDK to call selectors that the object does not support.
The app should continue running normally without crashing, even if IAM data is invalid or incomplete.

Stack Traace:

Fatal Exception: NSInvalidArgumentException
0  CoreFoundation                 0x11a2ec __exceptionPreprocess
1  libobjc.A.dylib                0x31a7c objc_exception_throw
2  CoreFoundation                 0x18467c +[NSObject(NSObject) _copyDescription]
3  CoreFoundation                 0x31b84 ___forwarding___
4  CoreFoundation                 0x314f0 _CF_forwarding_prep_0
5  OneSignalInAppMessages         0xba80 __77-[OSMessagingController attemptFetchWithRetries:rywData:attempts:retryLimit:]_block_invoke.90
6  OneSignalCore                  0x9e50 -[OneSignalClient handleJSONNSURLResponse:data:error:isAsync:withRequest:onSuccess:onFailure:]
7  OneSignalCore                  0x9338 __54-[OneSignalClient executeRequest:onSuccess:onFailure:]_block_invoke
8  CFNetwork                      0x30750 __40-[__NSURLSessionLocal taskForClassInfo:]_block_invoke
9  CFNetwork                      0x30510 __49-[__NSCFLocalSessionTask _task_onqueue_didFinish]_block_invoke_2
10 libdispatch.dylib              0x1aac _dispatch_call_block_and_release
11 libdispatch.dylib              0x1b584 _dispatch_client_callout
12 libdispatch.dylib              0xa2d0 _dispatch_lane_serial_drain
13 libdispatch.dylib              0xade0 _dispatch_lane_invoke
14 libdispatch.dylib              0x151dc _dispatch_root_queue_drain_deferred_wlh
15 libdispatch.dylib              0x14a60 _dispatch_workloop_worker_thread
16 libsystem_pthread.dylib        0x4660 _pthread_wqthread
17 libsystem_pthread.dylib        0x19f8 start_wqthread

OneSignal iOS SDK version

5.2.8

iOS version

16

Specific iOS version

* iOS 15 
* iOS 16
* iOS 17 (seen on multiple devices)

Relevant log output

Fatal Exception: NSInvalidArgumentException
0  CoreFoundation                 0x11a2ec __exceptionPreprocess
1  libobjc.A.dylib                0x31a7c objc_exception_throw
2  CoreFoundation                 0x18467c +[NSObject(NSObject) _copyDescription]
3  CoreFoundation                 0x31b84 ___forwarding___
4  CoreFoundation                 0x314f0 _CF_forwarding_prep_0
5  OneSignalInAppMessages         0xba80 __77-[OSMessagingController attemptFetchWithRetries:rywData:attempts:retryLimit:]_block_invoke.90
6  OneSignalCore                  0x9e50 -[OneSignalClient handleJSONNSURLResponse:data:error:isAsync:withRequest:onSuccess:onFailure:]
7  OneSignalCore                  0x9338 __54-[OneSignalClient executeRequest:onSuccess:onFailure:]_block_invoke
8  CFNetwork                      0x30750 __40-[__NSURLSessionLocal taskForClassInfo:]_block_invoke
9  CFNetwork                      0x30510 __49-[__NSCFLocalSessionTask _task_onqueue_didFinish]_block_invoke_2
10 libdispatch.dylib              0x1aac _dispatch_call_block_and_release
11 libdispatch.dylib              0x1b584 _dispatch_client_callout
12 libdispatch.dylib              0xa2d0 _dispatch_lane_serial_drain
13 libdispatch.dylib              0xade0 _dispatch_lane_invoke
14 libdispatch.dylib              0x151dc _dispatch_root_queue_drain_deferred_wlh
15 libdispatch.dylib              0x14a60 _dispatch_workloop_worker_thread
16 libsystem_pthread.dylib        0x4660 _pthread_wqthread
17 libsystem_pthread.dylib        0x19f8 start_wqthread

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[nan-li]

Hi @dipak-dr-iOS thanks for reporting. I see you are on 5.2.8, and this was previously reported in #1526.

The fix has been released in Release 5.2.9. Please update and let me know if you are still experiencing any issues.