caddyserver/caddy · error

failed to decode JSON response: %v

Error message

failed to decode JSON response: %v

What it means

Error "failed to decode JSON response: %v" thrown in caddyserver/caddy.

Source

Thrown at modules/caddypki/command.go:221

	return caddy.ExitCodeSuccess, nil
}

// rootCertFromAdmin makes the API request to fetch the root certificate for the named CA via admin API.
func rootCertFromAdmin(adminAddr string, caID string) (*x509.Certificate, error) {
	uri := path.Join(adminPKIEndpointBase, "ca", caID)

	// Make the request to fetch the CA info
	resp, err := caddycmd.AdminAPIRequest(adminAddr, http.MethodGet, uri, make(http.Header), nil)
	if err != nil {
		return nil, fmt.Errorf("requesting CA info: %v", err)
	}
	defer resp.Body.Close()

	// Decode the response
	caInfo := new(caInfo)
	err = json.NewDecoder(resp.Body).Decode(caInfo)
	if err != nil {
		return nil, fmt.Errorf("failed to decode JSON response: %v", err)
	}

	// Decode the root cert
	rootBlock, _ := pem.Decode([]byte(caInfo.RootCert))
	if rootBlock == nil {
		return nil, fmt.Errorf("failed to decode root certificate: %v", err)
	}
	rootCert, err := x509.ParseCertificate(rootBlock.Bytes)
	if err != nil {
		return nil, fmt.Errorf("failed to parse root certificate: %v", err)
	}

	return rootCert, nil
}

View on GitHub (pinned to 50e54ee279)

Solutions

1. Check that the admin endpoint returned a valid CA info response; the server may be running an incompatible version.

When it happens

Trigger: Thrown at modules/caddypki/command.go:221 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

AI-assisted analysis of caddyserver/caddy@50e54ee279 (2026-08-15). Data as JSON: /api/errors/1c6121ff9c85ba96. Report an issue: GitHub.