[release/v2.0] docs: add v2.0 release notes

docs/sources/release-notes/v2-0.md

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+---
+title: Version 2.0 release notes
+menuTitle: V2.0
+description: Release notes for Grafana Pyroscope 2.0
+weight: 680
+---
+
+## Version 2.0.0 release notes
+
+The Pyroscope team is excited to present Grafana Pyroscope 2.0.0.
+
+Pyroscope 2.0 makes the v2 storage architecture (segment-writer, query-backend, metastore, compaction-worker) the default for OSS users. v2 writes profiles directly to object storage and removes the need for in-memory ingesters, simplifying operations and reducing resource usage at scale. v1 remains available via an opt-in flag so existing deployments can upgrade without data loss.
+
+This release contains breaking changes. Review the [v1 to v2 migration guide](../../reference-pyroscope-v2-architecture/migrate-from-v1/) before upgrading.
+
+Notable changes are listed below. For the full diff, check out the [2.0.0 changelog](https://github.com/grafana/pyroscope/compare/v1.21.0...v2.0.0).
+
+### Breaking changes
+
+* Go module path bumped to `github.com/grafana/pyroscope/v2`. Library consumers must update their imports ([#5073](https://github.com/grafana/pyroscope/pull/5073))
+* Default write path flipped from `ingester` to `segment-writer`. Set `-write-path=ingester` to preserve v1 behavior ([#5038](https://github.com/grafana/pyroscope/pull/5038))
+* Default storage backend flipped from empty to `filesystem` ([#5038](https://github.com/grafana/pyroscope/pull/5038))
+* New `-architecture.storage` flag (`v1` | `v1-v2-dual` | `v2`), default `v1-v2-dual` ([#5038](https://github.com/grafana/pyroscope/pull/5038))
+* Error at startup when `-architecture.storage` includes v2 and no object-storage backend is configured ([#5074](https://github.com/grafana/pyroscope/pull/5074))
+* Default filesystem paths moved under `./data/v2/` ([#5038](https://github.com/grafana/pyroscope/pull/5038))
+* Removed `PYROSCOPE_V2_EXPERIMENTAL` environment variable ([#5038](https://github.com/grafana/pyroscope/pull/5038))
+* Removed legacy positional `server` argument from the `pyroscope` binary ([#5038](https://github.com/grafana/pyroscope/pull/5038))
+* Label sanitization disabled by default; UTF-8 label names with dots are accepted as-is. Set `-validation.disable-label-sanitization=false` to restore previous behavior ([#5038](https://github.com/grafana/pyroscope/pull/5038))
+* Helm chart 2.0.0 replaces `all.enable-v1-write-path` / `all.enable-v1-read-path` with `architecture.storage`, removes `persistence.shared` and `migration.queryBackend`, and forwards `ingesterWeight` / `segmentWriterWeight` correctly ([#5076](https://github.com/grafana/pyroscope/pull/5076))
+
+### Enhancements
+
+* **profilecli**: Add `debuginfo upload` subcommand ([#5080](https://github.com/grafana/pyroscope/pull/5080))
+
+### Fixes
+
+* Fix missed v1 import path in `pyroscope_test.go` after module bump to v2 ([#5077](https://github.com/grafana/pyroscope/pull/5077))
+* **make**: Add `frontend/build` dependency to `reference-help` target ([#5071](https://github.com/grafana/pyroscope/pull/5071))
+
+### Documentation
+
+* Improve v1 → v2 migration docs: switch to `--reset-then-reuse-values`, target chart 2.0.0 ([#5079](https://github.com/grafana/pyroscope/pull/5079))
+* Add v1.21 release notes ([#5082](https://github.com/grafana/pyroscope/pull/5082))
+* Fix contributors grid layout in README ([#5078](https://github.com/grafana/pyroscope/pull/5078))
+
+### Upgrade
+
+To upgrade from v1.21.x:
+
+1. Read the [v1 to v2 migration guide](../../reference-pyroscope-v2-architecture/migrate-from-v1/).
+2. If you import Pyroscope as a Go library, update imports to `github.com/grafana/pyroscope/v2`.
+3. If you deploy with Helm, upgrade to chart `2.0.0` and review the removed and renamed values listed above.
+4. If you run the binary directly and want to stay on v1 storage, set `-architecture.storage=v1` and `-write-path=ingester` explicitly — the previous defaults no longer apply.
+5. If you want to move to v2, configure object storage and set `-architecture.storage=v2` (or leave `v1-v2-dual` during the transition).