With the release of iOS 15.4, we've noticed crashes starting to appear for older iPhones (iPhone X being the newest one). Firebase Crashlytics mentions: "lazy protocol witness table accessor for type * and conformance *" for the crashed thread. This happens on several occasions with different classes... The stack trace (redacted) looks like follows: 0 libsystem_kernel.dylib 0x1bb5febbc __pthread_kill + 8 1 libsystem_pthread.dylib 0x1dbfb3854 pthread_kill + 208 2 libsystem_c.dylib 0x18b5c80b0 __abort + 124 3 libsystem_c.dylib 0x18b5736b0 abort + 136 4 libswiftCore.dylib 0x1858bb01c swift::fatalError(unsigned int, char const*, ...) + 140 5 libswiftCore.dylib 0x1858c4698 swift::MetadataAllocator::Allocate(unsigned long, unsigned long) + 516 6 libswiftCore.dylib 0x1858c51f4 _swift_getGenericMetadata(swift::MetadataRequest, void const* const*, swift::TargetTypeContextDescriptor<swift::InProcess> const*) + 1004 7 libswiftCore.dylib 0x1858a8d68 __swift_instantiateCanonicalPrespecializedGenericMetadata + 32 8 Application 0x103388304 9 Application 0x10338811c 10 Application 0x102cee9b4 11 Application 0x102ceea08 12 Application 0x102cfab28 13 Application 0x10ad195d0 14 Application 0x10ad18ed8 15 Application 0x10ad19d9c 16 Application 0x10ad151f8 17 Application 0x10ad16090 18 libdispatch.dylib 0x180b6f094 _dispatch_call_block_and_release + 24 19 libdispatch.dylib 0x180b70094 _dispatch_client_callout + 16 20 libdispatch.dylib 0x180b5474c _dispatch_root_queue_drain + 612 21 libdispatch.dylib 0x180b54dec _dispatch_worker_thread2 + 160 22 libsystem_pthread.dylib 0x1dbfa7dd4 _pthread_wqthread + 224 23 libsystem_pthread.dylib 0x1dbfa793c start_wqthread + 8 I hope someone can provide some insights to fix this.