micro/go-micro · error

ErrEncodingToken

ErrEncodingToken

Error message

error encoding the token

What it means

ErrEncodingToken (message "error encoding the token") is returned by Provider.Generate in auth/jwt/token when the token cannot be serialized/encoded into a JWT. The declared sentinel is returned whenever the underlying encode step fails inside Generate, so callers can distinguish encoding failure from lookup or inspect errors.

Source

Thrown at auth/jwt/token/token.go:14

package token

import (
	"errors"
	"time"

	"go-micro.dev/v6/auth"
)

var (
	// ErrNotFound is returned when a token cannot be found.
	ErrNotFound = errors.New("token not found")
	// ErrEncodingToken is returned when the service encounters an error during encoding.
	ErrEncodingToken = errors.New("error encoding the token")
	// ErrInvalidToken is returned when the token provided is not valid.
	ErrInvalidToken = errors.New("invalid token provided")
)

// Provider generates and inspects tokens.
type Provider interface {
	Generate(account *auth.Account, opts ...GenerateOption) (*Token, error)
	Inspect(token string) (*auth.Account, error)
	String() string
}

type Token struct {
	// The actual token
	Token string `json:"token"`
	// Time of token creation
	Created time.Time `json:"created"`
	// Time of token expiry
	Expiry time.Time `json:"expiry"`

View on GitHub (pinned to 24529f1404)

Solutions

1. Check the provider's key configuration (private key env var/option) is present and valid PEM before calling Generate
2. Validate the key can parse/sign by running a minimal Generate in a startup health check
3. Ensure the account/claims being encoded contain only serializable values
4. Pin/upgrade the jwt dependency if an algorithm incompatibility was introduced

Example fix

// before: provider built with an empty private key, Generate fails with ErrEncodingToken
p := token.NewProvider() // no key configured
p.Generate(account)
// after: configure a valid key up front and fail fast at startup
p := token.NewProvider(token.WithPrivateKey(signingKey))
if _, err := p.Generate(account); err != nil { log.Fatalf("token signing misconfigured: %v", err) }

// validate signing key at startup before any Generate call
func validateKey(pem string) error {
    if strings.TrimSpace(pem) == "" { return errors.New("JWT signing key is empty") }
    if !strings.Contains(pem, "-----BEGIN") { return errors.New("JWT signing key is not PEM encoded") }
    return nil
}
if err := validateKey(os.Getenv("JWT_PRIVATE_KEY")); err != nil { log.Fatal(err) }

func isEncodingError(err error) bool {
    return errors.Is(err, token.ErrEncodingToken)
}

tok, err := provider.Generate(account)
if err != nil {
    if errors.Is(err, token.ErrEncodingToken) {
        return fmt.Errorf("token encoder misconfigured, check signing key: %w", err)
    }
    return err
}

When it happens

Trigger: Provider.Generate is called and the internal encoding (e.g. JWT claims serialization or signing) returns an error, most commonly an invalid or missing signing key configured on the provider.

Common situations: JWT_PRIVATE_KEY / signing key env var unset or malformed so the encoder is misconfigured; key file unreadable at runtime; using a key algorithm unsupported by the encoding path after a library version change.

Related errors

• ErrInvalidToken
• ErrNotFound
• ErrInvalidToken
• ErrEncodingMessage
• ap2: mandate id is required

AI-assisted analysis of micro/go-micro@24529f1404 (2026-09-01). Data as JSON: /api/errors/0b2db8c3fc248a1c. Report an issue: GitHub.