Reliably reproduces like this:

$ CONF=linux-aarch64-server-fastdebug make test TEST=gc/shenandoah/TestWithLogLevel.java TEST_VM_OPTS="-XX:StartFlightRecording"

# Internal Error (/home/shipilev/shipilev-jdk/src/hotspot/share/gc/shared/gcId.cpp:60), pid=24855, tid=24999
# assert(gc_id != undefined()) failed: Using undefined GC id.

Stack: [0x0000fffe75e02000,0x0000fffe76000000], sp=0x0000fffe75ffe350, free space=2032k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0xd0758c] GCId::current()+0x100 (gcId.cpp:60)
V [libjvm.so+0x5eef04] AgeTableTracer::send_tenuring_distribution_event(unsigned int, unsigned long)+0x64 (ageTableTracer.cpp:32)
V [libjvm.so+0x5ee970] AgeTable::print_on(outputStream*)+0x60 (ageTable.cpp:136)
V [libjvm.so+0x163a90c] ShenandoahEvacuationTracker::print_evacuations_on(outputStream*, ShenandoahEvacuationStats*, ShenandoahEvacuationStats*)+0x1c0 (shenandoahEvacTracker.cpp:123)
V [libjvm.so+0x1667c54] ShenandoahGenerationalControlThread::process_phase_timings() const+0x10c (shenandoahGenerationalControlThread.cpp:351)
V [libjvm.so+0x166b2dc] ShenandoahGenerationalControlThread::run_gc_cycle(ShenandoahGenerationalControlThread::ShenandoahGCRequest const&)+0x234 (shenandoahGenerationalControlThread.cpp:310)
V [libjvm.so+0x166b80c] ShenandoahGenerationalControlThread::run_service()+0x140 (shenandoahGenerationalControlThread.cpp:79)
V [libjvm.so+0x9e56c8] ConcurrentGCThread::run()+0x28 (concurrentGCThread.cpp:47)
V [libjvm.so+0x18e10d8] Thread::call_run()+0x134 (thread.cpp:231)
V [libjvm.so+0x1431458] thread_native_entry(Thread*)+0x12c (os_linux.cpp:877)
C [libpthread.so.0+0x7230] start_thread+0xb0
Registers: