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. It fails the run. 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

Terminal

[KUBB_FORMAT_FAILED]: formatter failed
  see: https://kubb.dev/docs/5.x/reference/diagnostics/kubb-format-failed

See also

• Configuration
• KUBB_LINT_FAILED
• Diagnostics reference