# MLflow v3.12.0

- Product: MLflow (https://whatsnew.fyi/product/mlflow)
- Vendor: LF AI & Data
- Date: 2026-05-05
- Version: v3.12.0
- Original notes: https://github.com/mlflow/mlflow/releases/tag/v3.12.0
- Permalink: https://whatsnew.fyi/product/mlflow/releases/v3.12.0

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** — Store multimodal content in tracing spans as artifact attachments with mlflow-attachment:// style URI and rich rendering for PDFs, audio, and images
- **added** — Support for Codex, Gemini, and Qwen coding agent tracing
- **added** — Set guardrails on gateway endpoints to prevent unsafe or non-compliant model inputs and outputs
- **added** — Pagination for traces tab to improve initial load time and page responsiveness
- **added** — Record caller in gateway traces from request headers
- **added** — Portkey as a supported AI Gateway provider
- **added** — Add last_updated_at field to model catalog entries
- **added** — Enable third-party scorer registration in OSS MLflow
- **added** — Auto-start SQL warehouse before V4/V5 MLflow tracing calls
- **added** — Support model_kwargs in DeepEval scorers for LLM parameter control
- **added** — Application Default Credentials auth mode for Vertex AI gateway
- **added** — Share button to trace detail view
- **added** — mlflow.diffusers flavor for diffusion model LoRA adapters
- **added** — Add size limit for trace attachments
- **added** — JSON OTLP encoding support for trace ingestion
- **added** — Presigned upload URL endpoint for S3 artifact uploads
- **added** — Add @mlflow/vercel for better Vercel AI SDK tracing in Databricks UC
- **added** — Guardrail base class and JudgeGuardrail implementation
- **added** — Configurable provider allow/deny list to AI Gateway
- **added** — mlflow db move-resources command to move resources between workspaces

MLflow 3.12.0 includes several major features and improvements

###### Major New Features

- **🖼️ Multimodal Tracing**: Users can now store multimodal content in tracing spans as artifact attachments instead of inline binary data. We've also patched the UI to support the new mlflow-attachment:// style URI, with rich rendering available for PDFs, audio, and images.
- **🤖 Codex, Gemini, Qwen coding agent tracing support**: Similar to our Claude Code tracing integration, we've now added support for the Codex, Gemini, and Qwen coding agent platforms as well!
- **🛡️ Gateway guardrails**: You can now set guardrails on your gateway endpoints to prevent unsafe or non-compliant model inputs and outputs. Try it out in the MLflow UI!
- **⚡ Trace table pagination**: The traces tab is now paginated, rather than fetching all traces up to a limit of 1000. This improves initial load time, and makes the page feel more responsive overall.

###### Breaking Changes

- [Scoring] Deprecate `enable_mlserver` in pyfunc serving backend (#22994, @B-Step62)

###### Other Assorted Features & Improvements:

- [UI] Add coding agents section to AI Gateway quick start (#23006, @TomeHirata)
- [Tracing] feat: record caller in gateway traces from request headers (#22926, @TomeHirata)
- [] Run guardrails on passthrough endpoints; skip `response_format` for non-chat payloads (#22856, @TomeHirata)
- [] Gateway: preserve client auth header for subscription-based CLI tools (`claude-cli`, `Codex-Desktop`, `GeminiCLI`) (#22915, @TomeHirata)
- [Tracing] Expose Codex and Qwen Code hooks as installable CLI binaries (#22853, @kriscon-db)
- [Tracking / UI] Add Portkey as a supported AI Gateway provider (#22830, @sairavuri-sudo)
- [Tracking] Cache successful basic-auth credential checks to eliminate per-request PBKDF2 (#22817, @PattaraS)
- [] Add `last_updated_at` field to model catalog entries (#22838, @copilot-swe-agent)
- [Evaluation] Enable third-party scorer registration in OSS MLflow (#22634, @smoorjani)
- [] Add platform-side telemetry fields to Gateway invocation and budget events (#22557, @PattaraS)
- [Tracing] Auto-start SQL warehouse before V4/V5 MLflow tracing calls (#22798, @artjen)
- [Tracing] Migrate Claude Code tracing to TypeScript-based plugin for simpler installation and runtime handling. (#22338, @B-Step62)
- [Tracing] Add TypeScript Qwen Code tracing via Stop hook (#22411, @kriscon-db)
- [] Support `model_kwargs` in DeepEval scorers for LLM parameter control (#22494, @debu-sinha)
- [] Add Application Default Credentials auth mode for Vertex AI gateway (#22754, @harupy)
- [UI] Reorganize Settings into section-based routing with sub-sidebar navigation (#22743, @serena-ruan)
- [Tracing] Add TypeScript Codex CLI tracing via `notify` hook (#22410, @kriscon-db)
- [Tracing / UI] Add Share button to trace detail view (#22608, @alkispoly-db)
- [Docs / Models] Add `mlflow.diffusers` flavor for diffusion model LoRA adapters (#22253, @Rasaboun)
- [Tracing] Add size limit for trace attachments (#22575, @kriscon-db)
- [Tracing] Add `GeminiCliTranslator` for Gemini CLI OTLP span type mapping (#22409, @kriscon-db)
- [Tracing] Add JSON OTLP encoding support for trace ingestion (#22408, @kriscon-db)
- [Tracing] Extract `service.name` from OTLP resource attributes for usage telemetry (#22407, @kriscon-db)
- [Tracing] Add MLflow tracing spans to guardrail execution in gateway (#22581, @TomeHirata)
- [Tracing / UI] Add rendering size guards for large media content (#22574, @kriscon-db)
- [Tracking] #21037 Add presigned upload URL endpoint for S3 artifact uploads (#21039, @henishborad)
- [UI] Add Guardrails tab to endpoint editor (#22360, @TomeHirata)
- [UI] Add click-to-expand modal for trace attachment images (#22461, @kriscon-db)
- [UI] Enhance Gateway quick start cards with logos, multi-model options, and compact variant (#22513, @xq-yin)
- [Tracing] Add @mlflow/vercel for better Vercel AI SDK tracing in Databricks UC (#2210

_[Truncated at 4000 characters — full notes: https://github.com/mlflow/mlflow/releases/tag/v3.12.0]_