failed to parse Markdown attributes; you may need to quote t

Error message

failed to parse Markdown attributes; you may need to quote the values

What it means

Hugo's Goldmark code-block renderer found a `{...}` attribute block in a fenced code block's info string but Goldmark's `parser.ParseAttributes` failed to parse it. Hugo supports Markdown attributes on code fences (e.g. ```` ```go {linenos=true} ````), and this error surfaces when the attribute syntax inside the braces is malformed — commonly unquoted values containing spaces or special characters.

Source

Thrown at markup/goldmark/codeblocks/render.go:166

			if attrEndIdx == -1 && char == '{' {
				attrStartIdx = idx
			}
			if attrStartIdx != -1 && char == '}' {
				attrEndIdx = idx
				break
			}
		}

		if attrStartIdx != -1 && attrEndIdx != -1 {
			n := ast.NewTextBlock() // dummy node for storing attributes
			attrStr := infostr[attrStartIdx : attrEndIdx+1]
			if attrs, hasAttr := parser.ParseAttributes(text.NewReader(attrStr)); hasAttr {
				for _, attr := range attrs {
					n.SetAttribute(attr.Name, attr.Value)
				}
				return n.Attributes(), "", nil
			} else {
				return nil, string(attrStr), errors.New("failed to parse Markdown attributes; you may need to quote the values")
			}
		}
	}
	return nil, "", nil
}

View on GitHub ↗ (pinned to 8a468df065)

Solutions

Quote attribute values: change `{title=My File}` to `{title="My File"}`.
Check attribute syntax matches Hugo docs: comma- or space-separated key=value pairs inside a single `{...}` block, e.g. `{linenos=inline, hl_lines=[2,3]}`.
If the braces are part of the language/info text and not attributes, remove or escape them from the info string.
Run `hugo` with `-v` to identify the offending file, then fix that code fence.

Example fix

```go {title=my file, linenos=true}   <!-- before: unquoted value with space -->
```go {title="my file", linenos=true} <!-- after -->

Defensive patterns

Strategy: validation

Validate before calling

// Lint fences before build: quote attribute values containing spaces/commas
// ```go {linenos=true, style="monokai"} — quote anything non-alphanumeric
re := regexp.MustCompile("^```\\w+\\s*\\{(.*)\\}")
// verify each attr parses as key=value with quoted strings for complex values

Try / catch

if err := hugolib.Build(...); err != nil {
    if strings.Contains(err.Error(), "failed to parse Markdown attributes") {
        // report offending file/line from the wrapped error; fix the fence, don't retry
    }
}

Prevention

Quote code-fence attribute values that contain spaces, commas, or special characters
Keep attribute lists in the documented `{key=value, key2="v 2"}` form
Add a CI markdown-lint step that scans fences for unquoted complex values

When it happens

Trigger: Rendering a fenced code block whose info string contains `{` and `}` with content that fails Goldmark attribute parsing — e.g. ```` ```bash {style=monokai theme} ```` or values with spaces/commas/special chars not wrapped in quotes. Requires `markup.goldmark.parser.attribute.block` or code-fence attribute handling to reach codeblocks/render.go:166 via `getAttributes`.

Common situations: Adding highlight options like `{linenos=table,hl_lines=1-3}` with a typo, using unquoted string values containing spaces (`{title=My File}`), copying attribute snippets from other SSGs with incompatible syntax, or curly braces in the info string that aren't meant as attributes.

Related errors

AI-assisted analysis of gohugoio/hugo@8a468df065 (2026-07-31). Data as JSON: /data/errors/2e0c3f744cf28696.json. Report an issue: GitHub ↗.