The problem I encountered was solved by myself:
using grant in spring cloud oauth2 project_ The type is password/OAuth/token to access and obtain the token_ error。 In postman, as shown in the figure below:

{
    "error": "server_error",
    "error_description": "Internal Server Error"
}

Java background error is as follows:

endpoint.TokenEndpoint : Handling error: NestedServletException, Handler dispatch failed; nested exception is java.lang.StackOverflowError

This problem is due to grant_ Type = password represents the user name and password authorization

/**
 * This configuration class, which mainly handles the verification of user names and passwords, etc.
 */
@Configuration
public class SecurityConfiger extends WebSecurityConfigurerAdapter {

    @Autowired
    private PasswordEncoder passwordEncoder;

    //register 1 authentication manager object to the container
    @Bean
    @Override
    public AuthenticationManager authenticationManagerBean() throws Exception {
        return super.authenticationManagerBean();
    }

    /**
     * Password encoding object (passwords are not encrypted)
     */
    @Bean
    public PasswordEncoder passwordEncoder() {
        return NoOpPasswordEncoder.getInstance();
    }

    /**
     * Handle username and password authentication
     * 1) The client passes username and password parameters to the authentication server
     * 2) Generally, username and password are stored in the database in the user table
     * 3) Verify the legitimacy of the currently passed user information based on the data in the user table
     */
    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        super.configure(auth);

        // In this method you can go to the associated database, currently we first configure the user information in memory
        // instantiate 1 user object (equivalent to 1 user record in the data table)
        UserDetails user = new User("admin","123456",new ArrayList<>());
        auth.inMemoryAuthentication()
                .withUser(user).passwordEncoder(passwordEncoder);
    }
}

Problem solving: the following are purely personal views: