Formatting not stable. Bailed after {} tries. This indicates

Error message

Formatting not stable. Bailed after {} tries. This indicates a bug in the formatter where it formats the file differently each time. As a temporary workaround you can ignore this file.

What it means

`deno fmt` verifies idempotency: it re-formats its own output up to 5 times and expects identical text. This error means each pass produced different text (a formatting cycle), so the formatter is non-idempotent for this file — a bug in the formatter, not in your code.

Source

Thrown at cli/tools/fmt.rs:1227

          }
          Ok(None) => {
            return Ok(Some(current_text));
          }
          Err(err) => {
            bail!(
              concat!(
                "Formatting succeeded initially, but failed when ensuring a ",
                "stable format. This indicates a bug in the formatter where ",
                "the text it produces is not syntactically correct. As a temporary ",
                "workaround you can ignore this file.\n\n{:#}"
              ),
              err,
            )
          }
        }
        count += 1;
        if count == 5 {
          bail!(
            concat!(
              "Formatting not stable. Bailed after {} tries. This indicates a bug ",
              "in the formatter where it formats the file differently each time. As a ",
              "temporary workaround you can ignore this file."
            ),
            count,
          )
        }
      }
    }
    None => Ok(None),
  }
}

/// Format stdin and write result to stdout.
/// Treats input as set by `--ext` flag.
/// Compatible with `--check` flag.
fn format_stdin(

View on GitHub (pinned to 9ad36f7a2c)

Solutions

Exclude the file: `// deno-fmt-ignore-file` at the top, or "fmt": { "exclude": [...] } in deno.json
Try a different Deno version — check the changelog for formatter fixes and upgrade
Reduce to a minimal reproduction and file it at github.com/denoland/deno/issues so the cycle gets fixed

Example fix

# before: `deno fmt src/big_file.ts` -> Formatting not stable. Bailed after 5 tries.

# after: first line of src/big_file.ts
// deno-fmt-ignore-file

Defensive patterns

Strategy: fallback

Try / catch

Catch the non-zero exit of `deno fmt <file>`; if stderr contains 'Formatting not stable', mark the file with `// deno-fmt-ignore-file` (or add to deno.json fmt.exclude) and re-run the batch, recording which files were skipped for follow-up.

Prevention

Test formatting in CI with `deno fmt --check` on the pinned Deno version
Upgrade Deno deliberately and re-run fmt across the repo once, in a dedicated commit
Report instability reproductions upstream — the workaround (ignore) is meant to be temporary

When it happens

Trigger: The loop in cli/tools/fmt.rs keeps getting next_pass_text != current_text; after the 5th pass (count == 5) it bails. Triggered by source constructs where two formatting rules keep flip-flopping (e.g. line-wrapping decisions in long expressions, comment alignment in markdown or CSS-in-template-literals).

Common situations: Formatter regressions after a Deno version bump; files with very long lines, dense destructuring, or markdown tables that alternate between two layouts; CI failing with 'not stable' on a file humans never touched.

Related errors

AI-assisted analysis of denoland/deno@9ad36f7a2c (2026-08-20). Data as JSON: /api/errors/58f55755ccf25cf4. Report an issue: GitHub.