Storage emulator shows `WARNING: sun.misc.Unsafe::arrayBaseOffset` on Java 24

[aalej]

[REQUIRED] Environment info

firebase-tools: v15.0.0

Platform: macOS

Java: v24

[REQUIRED] Test case

See "Steps to reproduce"

[REQUIRED] Steps to reproduce

1. Run firebase init storage
   • Please select an option: Don't set up a default project
   • What file should be used for Storage Rules? storage.rules
2. Run firebase emulators:start --project demo-project

[REQUIRED] Expected behavior

No waning message when starting the emulators

$ java --version
openjdk 22.0.2 2024-07-16
OpenJDK Runtime Environment Zulu22.32+15-CA (build 22.0.2+9)
OpenJDK 64-Bit Server VM Zulu22.32+15-CA (build 22.0.2+9, mixed mode, sharing)
$ firebase emulators:start --project demo-project
i  emulators: Starting emulators: storage
i  emulators: Detected demo project ID "demo-project", emulated services will use a demo configuration and attempts to access non-emulated services for this project will fail.

┌─────────────────────────────────────────────────────────────┐
│ ✔  All emulators ready! It is now safe to connect your app. │
│ i  View Emulator UI at http://127.0.0.1:4000/               │
└─────────────────────────────────────────────────────────────┘

┌──────────┬────────────────┬───────────────────────────────┐
│ Emulator │ Host:Port      │ View in Emulator UI           │
├──────────┼────────────────┼───────────────────────────────┤
│ Storage  │ 127.0.0.1:9199 │ http://127.0.0.1:4000/storage │
└──────────┴────────────────┴───────────────────────────────┘
  Emulator Hub host: 127.0.0.1 port: 4400
  Other reserved ports: 4500

Issues? Report them at https://github.com/firebase/firebase-tools/issues and attach the *-debug.log files.
 

[REQUIRED] Actual behavior

Warning message when starting the emulator WARNING: sun.misc.Unsafe::arrayBaseOffset has been called by com.google.protobuf.UnsafeUtil$MemoryAccessor

$ java --version
openjdk 24.0.2 2025-07-15
OpenJDK Runtime Environment Zulu24.32+13-CA (build 24.0.2+12)
OpenJDK 64-Bit Server VM Zulu24.32+13-CA (build 24.0.2+12, mixed mode, sharing)
$ firebase emulators:start --project demo-project
i  emulators: Starting emulators: storage
i  emulators: Detected demo project ID "demo-project", emulated services will use a demo configuration and attempts to access non-emulated services for this project will fail.
⚠  Unexpected rules runtime error: WARNING: A terminally deprecated method in sun.misc.Unsafe has been called
WARNING: sun.misc.Unsafe::arrayBaseOffset has been called by com.google.protobuf.UnsafeUtil$MemoryAccessor (file:/Users/alejandromarco/.cache/firebase/emulators/cloud-storage-rules-runtime-v1.1.3.jar)
WARNING: Please consider reporting this to the maintainers of class com.google.protobuf.UnsafeUtil$MemoryAccessor
WARNING: sun.misc.Unsafe::arrayBaseOffset will be removed in a future release


┌─────────────────────────────────────────────────────────────┐
│ ✔  All emulators ready! It is now safe to connect your app. │
│ i  View Emulator UI at http://127.0.0.1:4000/               │
└─────────────────────────────────────────────────────────────┘

┌──────────┬────────────────┬───────────────────────────────┐
│ Emulator │ Host:Port      │ View in Emulator UI           │
├──────────┼────────────────┼───────────────────────────────┤
│ Storage  │ 127.0.0.1:9199 │ http://127.0.0.1:4000/storage │
└──────────┴────────────────┴───────────────────────────────┘
  Emulator Hub host: 127.0.0.1 port: 4400
  Other reserved ports: 4500

Issues? Report them at https://github.com/firebase/firebase-tools/issues and attach the *-debug.log files.
 

Notes

This occurs on Java 24, no warning messages are shown on Java 22

AFAICT, the storage emulator works without any issues even with the warning message

[tenninebt]

FYI, it happens also using Java 25, same OS (macOS Tahoe, 26.2), only after upgrading to firebase-tools 15.

[BenJackGill]

+1 I am seeing the same