charmbracelet/glow · error

unable to render markdown: %w

Error message

unable to render markdown: %w

What it means

r.Render(content) runs the (possibly code-wrapped) markdown through glamour's goldmark-based ANSI renderer. It fails when the render pipeline errors - typically a malformed custom style that survives construction but breaks at render time, or an edge case in the content. With built-in styles this error is rare.

Source

Thrown at main.go:311

	r, err := glamour.NewTermRenderer(
		utils.GlamourStyle(style, isCode),
		glamour.WithWordWrap(int(width)), //nolint:gosec
		glamour.WithBaseURL(baseURL),
		glamour.WithPreservedNewLines(),
	)
	if err != nil {
		return fmt.Errorf("unable to create renderer: %w", err)
	}

	content := string(b)
	ext := filepath.Ext(src.URL)
	if isCode {
		content = utils.WrapCodeBlock(string(b), ext)
	}

	out, err := r.Render(content)
	if err != nil {
		return fmt.Errorf("unable to render markdown: %w", err)
	}

	// display
	switch {
	case pager || cmd.Flags().Changed("pager"):
		pagerCmd := os.Getenv("PAGER")
		if pagerCmd == "" {
			pagerCmd = "less -r"
		}

		fields, err := shell.Fields(pagerCmd, os.Getenv)
		if err != nil || len(fields) == 0 {
			return fmt.Errorf("unable to parse PAGER command: %s", pagerCmd)
		}
		c := exec.Command(fields[0], fields[1:]...) //nolint:gosec
		c.Stdin = strings.NewReader(out)
		c.Stdout = os.Stdout
		if err := c.Run(); err != nil {

View on GitHub (pinned to e3970c813d)

Solutions

1. Retry with a built-in style: glow -s dark <file>
2. Bisect the markdown: split the file to find the block that triggers the failure
3. Rebuild the custom style from the current default style template for your glamour version
4. Report upstream at charmbracelet/glamour if a minimal repro fails with built-in styles

out, err := r.Render(content)
if err != nil {
	fb, ferr := glamour.NewTermRenderer(glamour.WithStandardStyle("dark"))
	if ferr == nil {
		if out2, rerr := fb.Render(content); rerr == nil {
			out = out2
			err = nil
		}
	}
}
if err != nil { return fmt.Errorf("unable to render markdown: %w", err) }

When it happens

Trigger: Custom style missing required entries at render time; pathological or extremely large markdown exhausting memory; glamour version incompatible with the style file's keys; embedded content triggering a renderer error path.

Common situations: After upgrading glow/glamour with old custom styles, rendering documents with unusual constructs (huge tables, deeply nested blocks), styles copied from a different glamour major version.

Related errors

• error rendering markdown: %w
• unable to create renderer: %w
• error creating glamour renderer: %w

AI-assisted analysis of charmbracelet/glow@e3970c813d (2026-08-15). Data as JSON: /api/errors/90ece146d3ce3a9d. Report an issue: GitHub.