KUBB_FORMAT_FAILED: Format failed

Code: KUBB_FORMAT_FAILED Level: error

The formatter pass over the generated files failed. Formatting runs after generation. The files are written, but the run is marked failed.

What happened ​

When output.format is set, Kubb runs the configured formatter (oxfmt, biome, or prettier) over the output directory. A non-zero exit from the formatter shows up here, in the summary, and in --reporter json. Earlier versions swallowed it, so a broken formatter config went unnoticed.

How to fix it ​

• Confirm the formatter is installed and its config is valid.
• Run it manually on the output to see the underlying error, for example biome check --write ./src/gen.
• Remove or change output.format if you do not want a formatter pass.

Common causes ​

• The formatter is not installed in the project.
• The formatter config is invalid or points at a missing file.
• The formatter rejects the generated code.

Example output ​

[KUBB_FORMAT_FAILED]: formatter failed: Cannot find module 'oxfmt' fix: Check that the tool is installed and that the command and its config are correct. see: https://kubb.dev/docs/5.x/reference/diagnostics/kubb-format-failed

See also ​

• Configuration
• KUBB_LINT_FAILED
• Diagnostics reference