# New Release: Ultralytics v8.4.149

**URL:** <https://community.ultralytics.com/t/new-release-ultralytics-v8-4-149/2218>\
**Category:** Discussion\
**Tags:** ultralytics-official, releases, announcements\
**Created:** [September 12, 2026, 1:08pm UTC](https://community.ultralytics.com/t/new-release-ultralytics-v8-4-149/2218 "2026-09-12T13:08:13Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![glenn-jocher](https://sea1.discourse-cdn.com/flex001/user_avatar/community.ultralytics.com/glenn-jocher/32/83_2.png) [@glenn-jocher](https://community.ultralytics.com/u/glenn-jocher)\
**Post date:** [September 12, 2026, 1:08pm UTC](https://community.ultralytics.com/t/new-release-ultralytics-v8-4-149/2218/1 "2026-09-12T13:08:13Z")

</div>

# 🚀 Ultralytics v8.4.149 Released

**Ultralytics v8.4.149 improves training reliability, export compatibility, and Platform documentation, with important fixes for resumed runs, third-party integrations, and RT-DETR LiteRT accuracy.**

Review the complete update in the [v8.4.149 release notes](https://github.com/ultralytics/ultralytics/releases/tag/v8.4.149).

## 🌟 New Features

### SAM 3.1 is now the default smart annotation model

[Ultralytics Platform](https://platform.ultralytics.com) now lists **SAM 3.1** as its default smart annotation model, while SAM 3 and SAM 2.1 remain available.

Documentation also covers SAM 3.1 image prediction and current limitations, including unsupported Object Multiplex video tracking.

This update was contributed by [@glenn-jocher](https://github.com/glenn-jocher) in [PR #26145](https://github.com/ultralytics/ultralytics/pull/26145).

### AutoTrain documentation reorganized

AutoTrain documentation has moved to **Platform → Train → AutoTrain** , with clearer guidance covering:

- Baseline creation
- Controlled comparisons
- Experiment review
- Billing
- Team workspace usage

The documentation update was contributed by [@JaviChulvi](https://github.com/JaviChulvi) in [PR #26146](https://github.com/ultralytics/ultralytics/pull/26146).

## 🔄 Training and Integration Improvements

### More reliable checkpoint resume behavior

Resumed training now preserves the dataset stored in the checkpoint instead of unexpectedly switching to the default COCO8 dataset.

Additional improvements include:

- An explicitly supplied `data=` argument still takes priority.
- Missing datasets produce the expected dataset-not-found error.
- Checkpoints created with AMP disabled no longer attempt to load an empty AMP scaler state.

### Safer ONNX CUDA fallback

CUDA availability is now checked after ONNX Runtime creates its inference session. When the CUDA execution provider is unavailable, inference falls back to CPU with a clear warning instead of crashing.

### Improved Ray Tune compatibility

The Ray Tune integration now:

- Verifies that a compatible Ray version is installed.
- Reports training metrics through the current Ray Tune API.
- Reduces integration failures with newer Ray releases.

### More robust Weights & Biases runs

Automatically generated W&B run names are now limited to 64 characters, preventing crashes caused by overly long names.

### Clearer invalid-argument errors

CLI help is logged separately from syntax errors, helping the core error remain visible when output is truncated.

These reliability improvements were contributed by [@glenn-jocher](https://github.com/glenn-jocher) in [PR #26148](https://github.com/ultralytics/ultralytics/pull/26148).

## 🛠 Bug Fixes

### RT-DETR LiteRT export and inference accuracy

RT-DETR outputs are no longer incorrectly coordinate-normalized during LiteRT export or inference.

This brings LiteRT detection metrics much closer to ONNX results and improves consistency across Python, JavaScript, and npm deployment workflows.

The fix was contributed by [@onuralpszr](https://github.com/onuralpszr) in [PR #26142](https://github.com/ultralytics/ultralytics/pull/26142).

## 📦 Upgrade Today

Install or upgrade to the latest release with:

```bash
pip install -U ultralytics

```

Verify the installed version with:

```bash
yolo checks

```

For every commit included in this release, explore the [full v8.4.148 to v8.4.149 changelog](https://github.com/ultralytics/ultralytics/compare/v8.4.148...v8.4.149).

Give **Ultralytics v8.4.149** a try and share your results, questions, or feedback with the YOLO community. Thanks to all contributors and users helping make each release more reliable! 🙌