The following release notes are still in the process of being updated and cleaned up.

Release 9.0.1rc1 (2026-03-06)

Release Notes:

CLI:

• Add a new optional param to fail() to allow pretty-printing user erro… (#28817)

Configurability:

• Fix NPE caused by --repo_env with no value set (#28606) (#28640)
• Fix visibility for implicit deps of parent rules (#28627) (#28687)
• Refactor flag aliases to be passed around as labels (#28835)
• rules_python flag alias fixes (#28854)
• Support external repository labels in package_group (#28811) (#28895)
• Emit helpful error when using removed providers (#28360)

Core:

• Fix typo in SkyframeActionExecutor: Use lastEndTime instead of firstStartTime. (#28397)
• Prevent a Blaze crash when an aspect uses a test's TestRunner action. (#28756)

ExternalDeps:

• Revert "Upgrade Apache Commons Compress from 1.26.1 to 1.28.0" (https… (#28550)
• Fix disk cache failures on concurrent read-write access on Windows (h… (#28552)
• Error on single_version_override patch with wrong patch_strip (#28566) (#28622)
• Force rctx.{download_and,}extract to create user-readable files (#28531) (#28649)
• Fix StarlarkBaseExternalContext#checkInOutputDirectory (#28581) (#28677)
• Update and minimize the JDK for Windows arm64 builds (#28632) (#28714)
• Only use workspace facts for validation with --lockfile_mode=error (h… (#28767)
• Replant symlinks before caching repos (#28582) (#28785)

General:

• Release 9.0.0 (2026-01-20)
• Update all embedded JDKs to 25.0.2 (#28543) (#28548)
• Update buildozer to v8.5.1 (#28650) (#28679)

OSS:

• Support proto_library targets in @bazel_tools//src/main/protobuf (#28428) (#28502)
• Patch rules_graalvm for Bazel 9 (#28908)

Performance:

• Fix overflow in network metrics counters (#28856) (#28864)

Remote-Exec:

• Fix a deadlock in RemotePathChecker when using a disk cache (#28416) (#28465)
• Introduce RunfilesProxyArtifactValue. (#28516)

Rules-CPP:

• Fix clang warnings on Windows (#28748) (#28775)
• Cherry-pick cfedf9c into 9.0.1 (#28889)

Rules-Python:

• Add deprecation warning to --build_python_zip (#28586)

Acknowledgements:

This release contains contributions from many people at Google, as well as bazel.build machine account, Fabian Meumertzheim, Greg, Joseph Gette, Keith Smiley, Ted Kaplan, Will Stranton.

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