Crash on iOS with URLSessionInstrumentation using swizzling: 'Cannot set task delegate after resumption'

[maitbelarbi]

When using URLSessionInstrumentation in SwiftUI, the app crashes on iOS with the following exception:

*** Terminating app due to uncaught exception 'NSGenericException', reason: 'Cannot set task delegate after resumption'

Code Example:

self.urlSessionInstrumentation = URLSessionInstrumentation(
    configuration: URLSessionInstrumentationConfiguration(
        shouldInstrument: { request in
            // filtering applied
        }
    )
)

Environment:

iOS version: 26

Swift version: 6

OpenTelemetry SDK: 2.1.0

SwiftUI app using .task on a view

Steps to Reproduce:

Initialize URLSessionInstrumentation as above.

Trigger a network request with URLSession.

App crashes with the exception.

Expected behavior:
The instrumentation should not crash the app, even if URLSession tasks are resumed/swizzled.

Additional context:

The crash seems related to swizzling and delegate reassignment.

Occurs regardless of shouldInstrument filtering.

[nachoBonafonte]

could you provide a simple code/project that reproduces your issue?

[bryce-b]

Base off the information available, this appears like there may be a network request fired before the instrumentation is finished swizzling. Where in your application are you initializing the session instrumentation? If you initialize it in your AppDelegate it should complete before the task is executed (which should only be firing once the view is visible, if I understand correctly.) If this doesn't work, please provide a sample application that reproduced the issue.