There are two such instances observed:
- java/util/NavigableMap/LockStep.java with seed 1190769459568375.
- java/util/Collections/CheckedSetBash.java with an unknown seed.

Including hs_err and replay for LockStep (18437) and CheckedSetBash (18333). Stack trace for both is the same:

#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (src/hotspot/share/opto/graphKit.cpp:1943), pid=18437, tid=28419
# assert(_gvn.type(arg)->is_zero_type() && !t->inline_klass()->is_null_free()) failed: Unexpected argument type
#
# JRE version: Java(TM) SE Runtime Environment (26.0) (fastdebug build 26-jep401ea2-2025-11-28-1614533)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 26-jep401ea2-2025-11-28-1614533, mixed mode, tiered, compressed oops, compressed class ptrs, g1 gc, bsd-aarch64)
# Core dump will be written. Default location: core.18437
#
# If you would like to submit a bug report, please visit:
# https://bugreport.java.com/bugreport/crash.jsp
#

--------------- S U M M A R Y ------------

Command Line: -Xmx768m -XX:MaxRAMPercentage=6.25 -Dtest.boot.jdk=jdk-25_macos-aarch64_bin.tar.gz/jdk-25.jdk/Contents/Home -Djava.io.tmpdir=testoutput/test-support/jtreg_open_test_jdk_tier1_no_valhalla/tmp -ea -esa --enable-preview -Djava.library.path=2025-11-28-1614533/macosx-aarch64-debug.test/jdk/jtreg/native --patch-module=java.base=testoutput/test-support/jtreg_open_test_jdk_tier1_no_valhalla/patches/java.base -Djava.security.policy=file:./testoutput/test-support/jtreg_open_test_jdk_tier1_no_valhalla/jtreg.policy com.sun.javatest.regtest.agent.AgentServer -id 62 -logfile testoutput/test-support/jtreg_open_test_jdk_tier1_no_valhalla/jtData/agentServer.62.trace -allowSetSecurityManager -port 63915 -timeoutFactor 4.0

Host: "Macmini9,1" arm64, 8 cores, 16G, Darwin 24.6.0, macOS 15.7 (24G222)
Time: Fri Nov 28 17:26:59 2025 GMT elapsed time: 188.478871 seconds (0d 0h 3m 8s)

--------------- T H R E A D ---------------

Current thread (0x0000000136844810): JavaThread "C2 CompilerThread0" daemon [_thread_in_native, id=28419, stack(0x000000016d9a8000,0x000000016dbab000) (2060K)]


Current CompileTask:
C2:188478 8823 4 java.util.concurrent.ConcurrentSkipListMap$SubMap::loNode (50 bytes)

Stack: [0x000000016d9a8000,0x000000016dbab000], sp=0x000000016dba6c90, free space=2043k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.dylib+0x133f7b4] VMError::report(outputStream*, bool)+0x1b68 (graphKit.cpp:1943)
V [libjvm.dylib+0x13430b0] VMError::report_and_die(int, char const*, char const*, char*, Thread*, unsigned char*, void const*, void const*, char const*, int, unsigned long)+0x55c
V [libjvm.dylib+0x5f88f8] print_error_for_unit_test(char const*, char const*, char*)+0x0
V [libjvm.dylib+0x8980cc] GraphKit::set_arguments_for_java_call(CallJavaNode*, bool)+0x5bc
V [libjvm.dylib+0x3e2d2c] DirectCallGenerator::generate(JVMState*)+0x1d4
V [libjvm.dylib+0x3e716c] PredictedCallGenerator::generate(JVMState*)+0x24c
V [libjvm.dylib+0x3e5a40] CallGenerator::do_late_inline_helper()+0x898
V [libjvm.dylib+0x54c394] Compile::inline_incrementally_one()+0x25c
V [libjvm.dylib+0x54d118] Compile::process_late_inline_calls_no_inline(PhaseIterGVN&)+0x10c
V [libjvm.dylib+0x541da4] Compile::Optimize()+0xdac
V [libjvm.dylib+0x53fb54] Compile::Compile(ciEnv*, ciMethod*, int, Options, DirectiveSet*)+0x165c
V [libjvm.dylib+0x3e0e20] C2Compiler::compile_method(ciEnv*, ciMethod*, int, bool, DirectiveSet*)+0x1e4
V [libjvm.dylib+0x565170] CompileBroker::invoke_compiler_on_method(CompileTask*)+0x98c
V [libjvm.dylib+0x564470] CompileBroker::compiler_thread_loop()+0x3cc
V [libjvm.dylib+0x9b8d68] JavaThread::thread_main_inner()+0x1d0
V [libjvm.dylib+0x12713c4] Thread::call_run()+0xf0
V [libjvm.dylib+0xf8b6c0] thread_native_entry(Thread*)+0x138
C [libsystem_pthread.dylib+0x6bc8] _pthread_start+0x88
Lock stack of current Java thread (top to bottom):