The JWT token is not being recognized in the .NET Core 2 Web API.

edit

There are a few possible reasons why the JWT token is not being recognized in the .NET Core 2 Web API, including:

1. Incorrect authentication middleware configuration: Make sure that the authentication middleware is properly configured to validate the JWT token. This can be done in the ConfigureServices method of the Startup.cs file using the AddAuthentication and AddJwtBearer methods.

2. Incorrect placement of the authentication middleware: Make sure that the authentication middleware is placed before the routing middleware in the pipeline in the Configure method of the Startup.cs file. This ensures that the incoming requests are authenticated first before being processed by the controllers.

3. Incorrect token format: Make sure that the JWT token format is correct and includes the required information, such as the issuer, audience, expiration date, and signature. You can use a JWT decoder tool to verify the token format.

4. Incorrect token validation settings: Make sure that the token validation settings are correct, including the token issuer, audience, and expiration time. This can be done in the AddJwtBearer method by configuring the JWTBearerOptions.

5. Incorrect authorization policies: Make sure that the authorization policies are correctly configured to allow access to the controllers or endpoints. This can be done in the ConfigureServices method by using the AddAuthorization method and creating policies that match the roles or permissions required by the endpoints.

If none of the above solutions work, there may be a problem with the token generation or transmission process, or there may be other underlying issues in the application that require further debugging.