Javascript – i can't to fix CORS

When i register to my form it’s not work because :

Access to fetch at ‘http://127.0.0.1:8081/api/auth/register’ from origin ‘http://localhost:3000’ has been blocked by CORS policy: Response to preflight request doesn’t pass access control check: No ‘Access-Control-Allow-Origin’ header is present on the requested resource. If an opaque response serves your needs, set the request’s mode to ‘no-cors’ to fetch the resource with CORS disabled.

i use react js for my front end :

export default function Inscrit() {
    function Alerte(e, props) {
        e.preventDefault()
        fetch('http://127.0.0.1:8081/api/auth/register', {
            method: 'POST',
            mode: 'cors',
            credentials: "include",
            headers: {'Content-Type':'application/json'}})

    }
    return(
        <div>
            <h1>Inscrit toi !</h1>
            <form>
                <input type="text" placeholder="Nom" name='nom'/>
                <input type="text" placeholder="Prenom" name='prenom'/>
                <input type="email" placeholder="Email" name='email'/>
                <input type="password" placeholder="Mot de passe" name='password'/>
                <button type="submit" onClick={Alerte}>s'inscrire</button>
            </form>
        </div>
    )
}

and my back end in java eclipse also my Cors:

spring:
  cloud:
    gateway:
      globalcors:
        corsConfigurations:
          '[/**]':
            allowedOrigins: "http://127.0.0.1:3000"
            allowedHeaders: "*"
            allowedMethods:
            - GET
            - POST
            - PUT
            - DELETE