dagger/dagger · error

failed to update tsconfig.json: %w

Error message

failed to update tsconfig.json: %w

What it means

This error is returned by CreateOrUpdateTSConfigForModule when tsutils.UpdateTSConfigForModule cannot merge Dagger's required compilerOptions/paths into the module's existing tsconfig.json. It wraps the underlying cause (almost always invalid JSON in tsconfig.json) so the engine's output names the failing step. It only fires when a tsconfig.json already exists in the module source; a missing file would trigger the default-config path instead.

Source

Thrown at sdk/typescript/runtime/config_updator.go:34

	if err != nil {
		return nil, fmt.Errorf("failed to lookup for tsconfig.json: %w", err)
	}

	// If no tsconfig.json is found in the user module, we generate a default one.
	if !tsconfigExist {
		defaultTSConfigContent := tsutils.DefaultTSConfig()

		return dag.File("tsconfig.json", defaultTSConfigContent).Sync(ctx)
	}

	tsConfigContent, err := modSourceDir.File("tsconfig.json").Contents(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to read module's tsconfig.json: %w", err)
	}

	updatedTSConfigContent, err := tsutils.UpdateTSConfigForModule(tsConfigContent)
	if err != nil {
		return nil, fmt.Errorf("failed to update tsconfig.json: %w", err)
	}

	return dag.File("tsconfig.json", updatedTSConfigContent).Sync(ctx)
}

func CreateOrUpdateTSConfigForClient(ctx context.Context, modSourceDir *dagger.Directory, isRemote bool) (*dagger.File, error) {
	tsConfigExist, err := modSourceDir.Exists(ctx, "tsconfig.json")
	if err != nil {
		return nil, fmt.Errorf("failed to lookup for tsconfig.json: %w", err)
	}

	if !tsConfigExist {
		defaultTSConfigContent := tsutils.DefaultTSConfig()
		return dag.File("tsconfig.json", defaultTSConfigContent).Sync(ctx)
	}

	tsConfigContent, err := modSourceDir.File("tsconfig.json").Contents(ctx)
	if err != nil {

View on GitHub (pinned to 82ba2681db)

Solutions

1. Validate your tsconfig.json with a strict JSON parser (e.g. `jq . tsconfig.json`) and fix any syntax errors such as trailing commas or comments.
2. If the file uses jsonc-style comments, move them out or re-encode the file as plain UTF-8 (no BOM) JSON.
3. Temporarily delete tsconfig.json and re-run so Dagger generates a known-good default, then re-apply your custom settings on top.
4. Inspect the wrapped `%w` cause in the full error chain to identify the exact parse failure and file region.

Example fix

// before (tsconfig.json with trailing comma)
{
  "compilerOptions": {
    "strict": true,
  }
}

// after
{
  "compilerOptions": {
    "strict": true
  }
}

// run before dagger develop
jq empty tsconfig.json && echo ok || echo 'tsconfig.json is not valid strict JSON'

// bash wrapper
if ! dagger develop; then
  jq empty tsconfig.json || (rm tsconfig.json && dagger develop)  # regenerate default
fi

When it happens

Trigger: Running `dagger develop`/`dagger call` on a TypeScript module whose committed tsconfig.json exists but fails UpdateTSConfigForModule — typically because the file contains invalid JSON (comments, trailing commas, BOM) or is malformed such that the updater cannot parse/merge it.

Common situations: A developer hand-edited tsconfig.json and left a trailing comma or comment (jsonc content in a file parsed as strict JSON); the file was truncated by a bad merge; an encoding issue (UTF-16/BOM) from a Windows editor; or an old tsconfig format that the updater no longer understands.

Related errors

• unknown runtime: %s
• unknown runtime: %q
• failed to lookup for tsconfig.json: %w
• failed to read module's tsconfig.json: %w
• failed to update deno config paths: %w

AI-assisted analysis of dagger/dagger@82ba2681db (2026-09-05). Data as JSON: /api/errors/38e6adc394c6ee2b. Report an issue: GitHub.