grafana/k6 · error

invalid option %q

Error message

invalid option %q

What it means

An unknown key was found in K6_BROWSER_SCREENSHOTS_OUTPUT (file_persister.go:91). Only 'url', 'basePath', and 'header.<name>' are recognized; keys are case-sensitive, and anything else falls into the default branch.

Source

Thrown at internal/js/modules/k6/browser/browser/file_persister.go:91

			if hk == "" {
				return presignedURLConfig{}, fmt.Errorf("empty header key, received %q", s)
			}
		}

		switch k {
		case "url":
			u, err := url.ParseRequestURI(v)
			if err != nil && u.Scheme != "" && u.Host != "" {
				return presignedURLConfig{}, fmt.Errorf("invalid url %q", s)
			}
			presignedURL.getterURL = v
		case "basePath":
			presignedURL.basePath = v
		case "header":
			presignedURL.headers[hk] = hv
		default:
			return presignedURLConfig{}, fmt.Errorf("invalid option %q", k)
		}
	}

	if presignedURL.getterURL == "" {
		return presignedURLConfig{}, errors.New("missing required url")
	}

	return presignedURL, nil
}

View on GitHub (pinned to 93accf6570)

Solutions

1. Use exactly the three supported keys: url, basePath, header.<Name>
2. Fix plural/case mistakes: 'headers.1=' -> 'header.1=', 'URL=' -> 'url=', 'path=' -> 'basePath='
3. Remove options the parser does not support (there is no timeout/type/output option here)

Example fix

# before
K6_BROWSER_SCREENSHOTS_OUTPUT="url=https://h/,path=/shots,headers.1=a"
# after
K6_BROWSER_SCREENSHOTS_OUTPUT="url=https://h/,basePath=/shots,header.1=a"

const allowed = /^(url|basePath|header[.][^.]+)$/;
const bad = v.split(',').map(s => s.split('=')[0]).filter(k => !allowed.test(k));
if (bad.length) throw new Error(`unknown keys (allowed: url, basePath, header.Name): ${bad.join(', ')}`);

When it happens

Trigger: K6_BROWSER_SCREENSHOTS_OUTPUT contains 'URL=https://h/' (uppercase), 'path=/shots', 'output=remote', 'type=s3', or 'headers.1=x' - note 'headers.1' does not contain the substring 'header.', so it hits the default branch instead of being treated as a header.

Common situations: Guessing option names from similar tools; renaming from an older/other convention ('path' vs 'basePath'); typo 'headers.' plural; documentation drift between k6 versions.

Related errors

• format of value must be k=v, received %q
• parsing %s: %w
• format of header must be header.k=v, received %q
• empty header key, received %q
• invalid url %q

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/c20a506e4b9a8806. Report an issue: GitHub.