Zuul Proxy CORS header contains multiple values, headers repeated twice - Java Spring Boot CORS filter config

I also had the same issue, and i added the CorsFilter into the class where has @ EnableZuulProxy, but it still didn't solve my problem.

According to the github Q&A Zuul Access-Control-* Headers are duplicated

zuul.ignored-headers=Access-Control-Allow-Credentials, Access-Control-Allow-Origin

To add it to my zuul's bootstrap.properties, it works!!!

I had a similar problem but the issue was that I had CORS filter in both APIGateway and other services. IF thats not your case then try this CORS filter.

Add this to the class where you have @EnableZuulProxy in the API Gateway. This should do the trick i have a similar configuration on mine.

@Bean
public CorsFilter corsFilter() {
    final UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
    final CorsConfiguration config = new CorsConfiguration();
    config.setAllowCredentials(true);
    config.addAllowedOrigin("*");
    config.addAllowedHeader("*");
    config.addAllowedMethod("OPTIONS");
    config.addAllowedMethod("HEAD");
    config.addAllowedMethod("GET");
    config.addAllowedMethod("PUT");
    config.addAllowedMethod("POST");
    config.addAllowedMethod("DELETE");
    config.addAllowedMethod("PATCH");
    source.registerCorsConfiguration("/**", config);
    return new CorsFilter(source);
}