In the Keycloak server, you may receive a code-to-token-error message when trying to access your site. This error is caused by a security flaw in the Keycloak protocol, which is why you need to make sure that your website is protected against code-to-token-error messages. There are ways to prevent this error, and one of them is to disable the Logout method.
KC_RESTART token not being available
If you encounter the KC_RESTART token not being present error, then this is a result of a missing KC_RESTART token. When this error occurs, Keycloak attempts to get a new token using the “grant_type” request parameter, which defaults to zero. In order to successfully authenticate a user, it must have a nonce value that is not easily guessable. In addition, the nonce value must be hard to guess, and it is sent back to the client.
KC_TOKEN_ERROR token not being available
If you are receiving a KC_TOKEN_ERRor message, this may be because your access token is invalid. If your token expires, you must re-authenticate using the appropriate procedure. You can also disable the KC Plug-In service for at least an hour. A short-term solution to the problem is to refresh the token periodically. The refresh process requires a POST request at the /login/refreshToken and an access token value.