# MLflow v3.16.0 — MLflow 3.16.0

- Product: MLflow (https://whatsnew.fyi/product/mlflow)
- Vendor: LF AI & Data
- Date: 2026-09-04
- Version: v3.16.0
- Original notes: https://github.com/mlflow/mlflow/releases/tag/v3.16.0
- Permalink: https://whatsnew.fyi/product/mlflow/releases/v3.16.0

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **added** — Custom Trace Views that allow designing trace UI in plain English with MLflow Assistant building the view without config files or custom code
- **changed** — Redesigned Trace Experience is now the default with tighter row density, cleaner navigation, and redesigned span-tree view
- **added** — Reorder columns in traces and add configurable custom columns from any trace tag or metadata field
- **added** — Session grouping to find multi-turn conversations inline in the trace explorer
- **added** — Span Links as first-class support so relationships between spans are captured and navigable
- **changed** — Enable fail-closed authorization by default for basic-auth
- **removed** — Drop cross version testing for pyspark < 3.4.4
- **added** — Shell-based MLflow Tracing setup wizard
- **added** — Support per-user budget policies in the AI Gateway with USER scope and principal
- **added** — Expectation field to the traces table filter UI
- **added** — Configurable custom trace columns based on tags and metadata to Traces V4
- **deprecated** — Deprecate the experiment Sessions tab in favor of Traces session grouping
- **added** — TypeScript SDK support for logFeedback and typed trace assessments
- **added** — Support UC model services in built-in judges
- **added** — Configurable Huey storage URL for Redis in jobs
- **added** — External Secrets Operator support
- **added** — Image Grid toggle for run parameters
- **changed** — Increase experiment tag value limit to 20000
- **added** — TypeScript SDK support for MLFLOW_TRACKING_AUTH=kubernetes and kubernetes-namespaced
- **added** — Support optimizing chat-type prompts in optimize_prompts
- **added** — SpanLink support to TypeScript SDK

MLflow 3.16.0 includes several major features and improvements

###### Major New Features

- **🎨 Custom Trace Views**: Design your own trace UI in plain English — describe the view you want and the **MLflow Assistant** builds it for you, laying out exactly the fields you care about with no config files or custom code. Save, name, and reuse views per experiment so your whole team shares the same lens on your traces.
- **🔭 Redesigned Trace Experience (now default)**: The trace explorer has been rebuilt from the ground up and is now the default — tighter row density, cleaner navigation, and a redesigned span-tree view. **Reorder columns**, add **configurable custom columns** from any trace tag or metadata field, and find multi-turn conversations inline via **session grouping**.
- **🔗 Span Links**: Spans rarely stand alone. MLflow 3.16.0 adds first-class **span links** so relationships between spans — a retrieval step, a tool call, a downstream trace — are captured and navigable. Record links in your SDK and the trace explorer surfaces them in a dedicated Links tab to jump straight to the destination span.

Breaking changes:

- [Server-infra / Tracking] basic-auth: enable fail-closed authorization by default (#25308, @PattaraS)
- [Build / Models] Drop cross version testing for pyspark < 3.4.4 (#25098, @harupy)
- [Gateway / Tracing] fix: Serve FastAPI-native routers under `--static-prefix` (#24511, @SeiichiroYoshioka)

Features:

- [Evaluation / Tracing / Tracking] Add mlflow skills agent hints for GenAI anti-patterns (#25496, @james-fletcher-db)
- [Tracing] Add shell-based MLflow Tracing setup wizard (#25441, @B-Step62)
- [Gateway] Support per-user budget policies in the AI Gateway (USER scope + principal) (#24371, @joelrobin18)
- [Tracing / UI] Add trace-table column reordering to V4 traces tab (#25428, @joshuawong-db)
- [Tracing / UI] Add `Expectation` field to the traces table filter UI (#25460, @creater29)
- [Tracing / UI] Add saved views to MLflow demo (#25392, @joshuawong-db)
- [Tracing / UI] Add configurable custom trace columns (tags + metadata) to Traces V4 (#25427, @joshuawong-db)
- [Tracing / Tracking / UI] Refresh the Traces V4 table: row density, header, and navigation (#25354, @joshuawong-db)
- [Tracing / UI] Mount Traces V4 as the default traces experience (#25424, @joshuawong-db)
- [Tracing / UI] Port redesigned trace explorer (v2) to OSS (#25355, @joshuawong-db)
- [UI] Deprecate the experiment Sessions tab in favor of Traces session grouping (#25350, @joshuawong-db)
- [Evaluation / Tracing] feat(typescript): add `logFeedback` and typed trace assessments (#25169, @rajudandigam)
- [Tracing] Point coding agents at the MLflow tracing skill on `import mlflow` (#25247, @harupy)
- [Evaluation / Gateway] Support UC model services in built-in judges (#25246, @TomeHirata)
- [Tracing / UI] Enable `shouldEnableModelTraceExplorerCustomTraceView` in OSS (#25245, @aaronteo-db)
- [Tracking] jobs: add configurable Huey storage URL for Redis (#22653, @jeevan6996)
- [Tracking] [chart] Add optional External Secrets Operator support (#24523, @habibaikram1)
- [Evaluation] Enrich `mlflow scorers list --builtin` with the full scorer catalog (#25003, @joshuawong-db)
- [Tracing / UI] feat(ui): display scorer description in tooltip for custom judges (#22043, @adamgurary)
- [UI] Add Image Grid toggle for run parameters (#23705, @jdoughty04)
- [Tracing / Tracking / UI] [Custom View] Enforce saved view limit per experiment (#25064, @tanghaoji)
- [Tracking] [1/6] basic-auth: fail-closed authorization net + coverage guard (#25065, @PattaraS)
- [Build / Scoring] Bump model serving image to Ubuntu 24.04 and Python 3.11 (#25089, @harupy)
- [] Add SpanLink support to TypeScript SDK (#23480, @robinnarsinghranabhat)
- [Docs / Tracking] [Custom View] Increase experiment tag value limit to 20000 (#25062, @aaronteo-db)
- [Tracing / Tracking] feat(ts-sdk): add `MLFLOW_TRACKING_AUTH=kubernetes`/`kubernetes-namespaced` support (#24243, @robinnarsinghrana

_[Truncated at 4000 characters — full notes: https://github.com/mlflow/mlflow/releases/tag/v3.16.0]_