SpringBoot升级2.4.0所出现的问题：
When allowCredentials is true, allowedOrigins cannot contain the special value “*” since that cannot be set on the “Access-Control-Allow-Origin” response header. To allow credentials to a set of origins, list them explicitly or consider using “allowedOriginPatterns” instead.

解决方案：
跨域配置报错，将.allowedOrigins替换成.allowedOriginPatterns即可。
调整前：

package com.course.server.config;import org.springframework.context.annotation.Configuration;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;@Configuration
public class CorsConfig implements WebMvcConfigurer {@Overridepublic void addCorsMappings(CorsRegistry registry) {// 设置允许跨域的路由registry.addMapping("/**")// 设置允许跨域请求的域名.allowedOrigins("*").allowedHeaders(CorsConfiguration.ALL)// 设置允许的方法.allowedMethods(CorsConfiguration.ALL)// 是否允许证书（cookies）.allowCredentials(true)// 跨域允许时间.maxAge(3600);//1小时内不需要校验，发送OPTIONS请求}
}

调整后：

package com.course.server.config;import org.springframework.context.annotation.Configuration;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;@Configuration
public class CorsConfig implements WebMvcConfigurer {@Overridepublic void addCorsMappings(CorsRegistry registry) {// 设置允许跨域的路由registry.addMapping("/**")// 设置允许跨域请求的域名.allowedOriginPatterns("*").allowedHeaders(CorsConfiguration.ALL)// 设置允许的方法.allowedMethods(CorsConfiguration.ALL)// 是否允许证书（cookies）.allowCredentials(true)// 跨域允许时间.maxAge(3600);//1小时内不需要校验，发送OPTIONS请求}
}