Crash in URLSessionConfiguration init in Xcode 26.0 beta (17A5241e)

App & System Services Networking Beta Xcode Network CFNetwork

Created Jun ’25

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It's not yet fully clear why and when does this crash occur, but I'm creating this post so there's a centralized thread for this.

Some hints collected so far:

The crash is occurring for existing Xcode projects opened with new Xcode 26.0 beta (17A5241e); no one's been able to reproduce on a project created in Xcode 26. I even tried creating a project with Xcode 16.2 and open it in Xcode 26, but it's all working fine there (don't have older Xcode at the moment, to try with many versions)
It crashes right at the line of code that initializes URLSessionConfiguration. If you call URLSession() without parameters (which is deprecated as of iOS 13), the session initializes without the crash.
It's NOT occurring only for libraries installed through package manages. In a project where it crashes, one should be able to reproduce by adding URLSessionConfiguration.default as the first line in didFinishLaunchingWithOptions
It crashes when running an app on an iOS 26 simulator. (I don't have a device running beta iOS 26 to test on it!) It's working fine when running the app on a simulator or a device running iOS 18 or older.

Related issue on Firebase GitHub repo: https://github.com/firebase/firebase-ios-sdk/issues/14948

Sorry to not be able to provide more info at the moment. I wanted to report this so in case someone from Apple knows about it, we could at least get some feedback or workarounds, until fix is released -- and, to prevent us all from duplicating this report in repositories of each library, as this isn't related to libraries.

Answered by DTS Engineer in 846043022

this is still an issue with Xcode 26 Beta 2 as well.

Indeed.

For the record, the ‘lead bug’ here is FB18043319, and that’s not fixed in 26.0b2.

However, we do now fully understand the problem, so there’s no need for any more bug reports about this. Thanks to everyone who chipped in here.

I don’t have any info to share as to when this’ll be fixed. If this is causing you significant grief then I suggest that you temporarily apply the workaround suggested by salla.an in this post. I just happened to bump into this issue myself last week and that workaround got me past it.

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
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lazeebc OP

Hi! What is the current status of the bug? We started hitting this on xcode 26 beta and seems like the workaround does not work for us - calling nw_tls_create_options() before URLSession calls. I dont see any notes about this in beta3 as well.