#### [Abblix\.Jwt](https://www.abblix.com/en/docs/api/abblix-jwt 'index')
### [Abblix\.Jwt](https://www.abblix.com/en/docs/api/abblix-jwt/Abblix.Jwt 'Abblix\.Jwt')

## JwtError Enum

High\-level categories of JWT processing failures returned by the validator and by callers
that consume validated tokens\. Pair with [ErrorDescription](https://www.abblix.com/en/docs/api/abblix-jwt/Abblix.Jwt.JwtValidationError#Abblix.Jwt.JwtValidationError.ErrorDescription 'Abblix\.Jwt\.JwtValidationError\.ErrorDescription')
for a human\-readable explanation\. Categories let callers branch on the failure cause
without parsing the description string\.

```csharp
public enum JwtError
```
### Fields

###### `InvalidToken` 0 {#Abblix.Jwt.JwtError.InvalidToken}

The token cannot be accepted but does not fall into a more specific category below
\(for example, a missing or invalid issuer/audience/lifetime claim\)\.

###### `TokenAlreadyUsed` 1 {#Abblix.Jwt.JwtError.TokenAlreadyUsed}

The token is well\-formed and otherwise valid, but it has already been redeemed
in a context that allows only single use \(for example, an authorization code or a
one\-time login link\)\.

###### `TokenRevoked` 2 {#Abblix.Jwt.JwtError.TokenRevoked}

The token has been explicitly revoked by the issuer \(for example, after sign\-out,
password change, or administrative action\) and must no longer be honored\.

###### `MalformedToken` 3 {#Abblix.Jwt.JwtError.MalformedToken}

The compact JWS / JWE serialisation failed to parse: wrong dot\-separated\-segment
count, base64url decode failure, or the header/payload is not a JSON object\.

###### `InvalidAlgorithm` 4 {#Abblix.Jwt.JwtError.InvalidAlgorithm}

The `alg` header parameter is missing, names the unsecured `none`
algorithm where signed tokens are required, or falls outside the caller's
configured [AllowedSigningAlgorithms](https://www.abblix.com/en/docs/api/abblix-jwt/Abblix.Jwt.ValidationParameters#Abblix.Jwt.ValidationParameters.AllowedSigningAlgorithms 'Abblix\.Jwt\.ValidationParameters\.AllowedSigningAlgorithms') whitelist\.

###### `InvalidTokenType` 5 {#Abblix.Jwt.JwtError.InvalidTokenType}

The `typ` header parameter is missing or does not match the caller's
[ExpectedTokenTypes](https://www.abblix.com/en/docs/api/abblix-jwt/Abblix.Jwt.ValidationParameters#Abblix.Jwt.ValidationParameters.ExpectedTokenTypes 'Abblix\.Jwt\.ValidationParameters\.ExpectedTokenTypes') \(RFC 8725 §3\.11
token\-class\-confusion guard\)\.

###### `InvalidHeader` 6 {#Abblix.Jwt.JwtError.InvalidHeader}

A JOSE header parameter is malformed or violates a structural rule: the embedded
`jwk` is not a valid JWK, the `crit` array is malformed or names an
unknown extension, or a required header is missing for the chosen trust model\.

###### `InvalidSignature` 7 {#Abblix.Jwt.JwtError.InvalidSignature}

The JWS signature does not verify under the resolved signing key\.