denoland/deno · error

Found {} problem{}

Error message

Found {} problem{}

What it means

`deno publish` type-checks packages and refuses 'slow types' — public APIs lacking explicit types — collecting every diagnostic before failing. This is the summary error: N diagnostics were emitted (each printed above with file and position), and without --allow-slow-types the publish aborts.

Source

Thrown at cli/tools/publish/diagnostics.rs:68

      }
    }
    if errors > 0 {
      if has_slow_types_errors {
        log::error!(
          "This package contains errors for slow types. Fixing these errors will:\n"
        );
        log::error!(
          "  1. Significantly improve your package users' type checking performance."
        );
        log::error!("  2. Improve the automatic documentation generation.");
        log::error!("  3. Enable automatic .d.ts generation for Node.js.");
        log::error!(
          "\nDon't want to bother? You can choose to skip this step by"
        );
        log::error!("providing the --allow-slow-types flag.\n");
      }

      Err(anyhow!(
        "Found {} problem{}",
        errors,
        if errors == 1 { "" } else { "s" }
      ))
    } else {
      Ok(())
    }
  }

  pub fn has_error(&self) -> bool {
    self
      .diagnostics
      .lock()
      .iter()
      .any(|d| matches!(d.level(), DiagnosticLevel::Error))
  }

  pub fn push(&self, diagnostic: PublishDiagnostic) {

View on GitHub (pinned to 89f33cbef2)

Solutions

1. Fix the listed diagnostics: add explicit types at each reported file/position (start at the first error, later ones often cascade)
2. As a conscious stopgap, publish with --allow-slow-types (hurts consumer type-checking, docs, and .d.ts generation)
3. Run `deno publish --dry-run` locally and in CI so problems surface before a release

Example fix

// before
export function add(a, b) {
  return a + b;
}
// after
export function add(a: number, b: number): number {
  return a + b;
}

# catch slow types in CI before a release attempt
deno publish --dry-run

# release script: fail with guidance when the summary error appears
deno publish --dry-run 2>&1 | tee /tmp/publish.log
if grep -q "Found .* problem" /tmp/publish.log; then
  echo 'fix the listed diagnostics or pass --allow-slow-types deliberately' >&2
  exit 1
fi

When it happens

Trigger: `deno publish` (including --dry-run) where exported symbols rely on inference — missing parameter/return types on exported functions, implicit any in public class members — so the collector accumulated one or more errors.

Common situations: Porting untyped JS to JSR; exported helpers relying on inference; library surfaces where .d.ts generation and consumer type-checking speed depend on explicit types.

Related errors

• Failed to publish {} packages:
• Type checking failed: {}
• Invalid cron schedule: start=${start}, end=${end}, every=${e
• Invalid type for fetch: must be a function
• Failed to convert range to tsc text span: {:#}

AI-assisted analysis of denoland/deno@89f33cbef2 (2026-08-16). Data as JSON: /api/errors/cc5ecc566434c8bc. Report an issue: GitHub.