Release 8.4.0rc2 (2025-09-02)

Bazel 8.4.0 is a minor LTS release. It is fully backward compatible with Bazel 8.0 and contains selected changes by the Bazel community and Google engineers.

General

• Bazel releases that include a bundled JDK now use the system trust store for certificates by default. Set -Djavax.net.ssl.trustStore and -Djavax.net.ssl.trustStoreType via --host_jvm_args to override the default location. (#26681)
• The --experimental_cancel_concurrent_tests option now accepts the values on_passed, on_failed and never and cancels concurrent test runs on the first matching result. If enabled, it's now effective by default and no longer requires --test_strategy=standalone to be passed explicitly. (#26670)

Android

• Add better defaults for mobile-install flags (#26388)

CLI

• Bazel on MacOS now respects XDG directory settings: if the XDG_CACHE_HOME environment variable is set, the output root directory is ${XDG_CACHE_HOME}/bazel, like on Linux (#26773)

C / C++

• If a cc toolchain feature named shorten_virtual_includes is enabled, virtual include header files are linked under bin/_virtual_includes/<hash of target path> instead of bin/<target package path>/_virtual_includes/<target name>. This shortens the virtual include paths which is critical for mitigating the long path issue with MSVC on Windows. (#26532)
• Tool paths specified in cc_toolchain action configs are now normalized based on the current execution platform's OS rather than the host OS. In particular, Windows-style absolute paths are now treated as absolute paths when building on a Windows executor from a non-Windows host. (#26598)

Coverage

• Branches will always be merged as best as possible based on branch and block numbers during coverage report generation. (#26461)

External Dependencies

• Added --incompatible_compact_repo_mapping_manifest, which causes the repo mapping manifest file for runfiles to use a more compact format when necessary. (#26420)
• Modules backed by http_archive or git_repository no longer require a MODULE.bazel file to be contained in the source archive. (#26462)
• Repository content cache is disabled by default due to #26450, you can still manually enable it by setting --repo_contents_cache=.
• The new --module_mirrors flag accepts a comma-separated list of mirrors to use for source URLs provided by modules obtained from Bazel registries. (#26850)

Refer to the full list of commits for more details.

Acknowledgements:

This release contains contributions from many people at Google, as well as Aaron Sky, Adrian Vogelsgesang, Dmitry Ryabkov, Ed Schouten, Fabian Meumertzheim, George Gensure, Greg, James Judd, Jonathan Woodbury, Keith Smiley, Pelikan.B, Valentin Grigorev, Wade Carpenter, and Xavier Bonaventura.

Notice: Bazel installers contain binaries licensed under the GPLv2 with Classpath exception. Those installers should always be redistributed along with the source code.

Some versions of Bazel contain a bundled version of OpenJDK. The license of the bundled OpenJDK and other open-source components can be displayed by running the command bazel license. The vendor and version information of the bundled OpenJDK can be displayed by running the command bazel info java-runtime. The binaries and source-code of the bundled OpenJDK can be downloaded from our mirror server.

Security: All our binaries are signed with our public key 3D5919B448457EE0.