What’s New in Prometheus 3.0? UI Overhaul, Remote Write 2.0, UTF‑8 & OTLP Support

New User Interface

Prometheus 3.0 ships with a completely rewritten UI that is enabled by default. The UI uses a modern component stack, includes a PromLens‑style tree view, and supports UTF‑8 metric and label names. Users can temporarily switch back to the legacy UI with the old-ui feature flag.

Remote Write 2.0

Remote Write 2.0 extends the previous protocol with native support for:

metadata

exemplars

creation timestamps

native histograms

It adds string interning to reduce payload size and CPU usage during compression/decompression, and improves handling of partial writes by returning detailed error information.

Specification: https://prometheus.io/docs/specs/remote_write_spec_2_0/

UTF‑8 Support

Prometheus 3.0 accepts any valid UTF‑8 characters in metric names, label names, and label values, matching the behavior of the 2.x series. Exporters must emit UTF‑8 names; otherwise the legacy underscore‑escaping is applied. Queries can use quoted identifiers to reference UTF‑8 metrics, and the __name__ label can be set manually. Currently only the Go client library implements UTF‑8 support; other language clients will follow.

OTLP Support

Prometheus 3.0 includes a native OTLP receiver at the endpoint /api/v1/otlp/v1/metrics. Configuration follows the OTLP section of the Prometheus config reference.

Guide: https://prometheus.io/docs/guides/opentelemetry

Configuration reference: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#:%7E:text=Settings%20related%20to%20the%20OTLP%20receiver%20feature

Native Histograms

Native histograms are a new metric type that uses exponentially increasing bucket boundaries, eliminating the need for manual bucket selection. The feature is experimental and disabled by default; enable it with: --enable-feature=native-histograms Text format support and related functions are still under design.

Breaking Changes & Migration

Version 3.0 introduces several breaking changes:

New feature flags (e.g., old-ui, native-histograms)

Configuration file syntax adjustments

PromQL updates (quoted identifiers for UTF‑8)

Scrape protocol modifications

Upgrade path: first upgrade to Prometheus 2.55, then to 3.0. Rolling back from 3.0 to 2.55 is supported; rollback to earlier 2.x releases is not.

Migration guide: https://prometheus.io/docs/prometheus/3.0/migration/

Performance Improvements

Benchmarks using the prombench macro‑benchmark suite show lower CPU and memory usage for the TSDB mode in 3.0 compared with 2.0 and 2.18 on an 8‑core, 49 GB node.

Benchmark source: https://github.com/prometheus/prometheus/pull/15366

References

Remote Write 2.0 spec: https://prometheus.io/docs/specs/remote_write_spec_2_0/

OTLP guide: https://prometheus.io/docs/guides/opentelemetry

OTLP configuration: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#:%7E:text=Settings%20related%20to%20the%20OTLP%20receiver%20feature

No‑suffix implementation proposal: https://github.com/prometheus/proposals/pull/39

Migration guide: https://prometheus.io/docs/prometheus/3.0/migration/

prombench macro‑benchmark: https://github.com/prometheus/prometheus/pull/15366

Binary downloads: https://prometheus.io/download/#prometheus

Container images: https://quay.io/repository/prometheus/prometheus?tab=tags