用户提供程序必须返回UserInterface对象，SYmfony 4登录错误

伙计我是Symfony 4的新手，

这是我的security.yaml，我的目的是从数据库登录加载用户

security:
   encoders:
       App\Entity\Login: 
          algorithm: bcrypt

providers:
    db_provider:
        entity:
            class: App\Entity\Login
            property: username

firewalls:
    dev:
        pattern: ^/(_(profiler|wdt)|css|images|js)/
        security: false
    main:
        provider: db_provider
        anonymous: ~
        form_login:
            login_path: login
            check_path: login
            default_target_path: postlogin

这是我的实体

class Login
{
/**
 * @ORM\Id()
 * @ORM\GeneratedValue()
 * @ORM\Column(type="integer")
 */
private $id;

/**
 * @ORM\Column(type="string", length=255)
 */
private $username;

/**
 * @ORM\Column(type="string", length=255)
 */
private $email;

/**
 * @ORM\Column(type="string", length=255)
 */
private $password;

public function getId()
{
    return $this->id;
}

public function getUsername(): ?string
{
    return $this->username;
}

public function setUsername(string $username): self
{
    $this->username = $username;

    return $this;
}

public function getEmail(): ?string
{
    return $this->email;
}

public function setEmail(string $email): self
{
    $this->email = $email;

    return $this;
}

public function getPassword(): ?string
{
    return $this->password;
}

public function setPassword(string $password): self
{
    $this->password = $password;

    return $this;
}

}

这是完整的错误

Symfony \ Component \ Security \ Core \ Exception \ AuthenticationServiceException：用户提供程序必须返回UserInterface对象 . 在C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ security \ Core \ Authentication \ Provider \ DaoAuthenticationProvider.php：85堆栈跟踪：＃0 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ http-foundation \ Session \ Storage \ NativeSessionStorage.php（142）：session_start（）＃1 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ http-foundation \ Session \ Storage \ NativeSessionStorage.php（299）：Symfony \ Component \ HttpFoundation \ Session \ Storage \ NativeSessionStorage-> start（）＃2 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ http-foundation \ Session \ Session.php（249）：Symfony \ Component \ HttpFoundation \ Session \ Storage \ NativeSessionStorage-> getBag（'attributes'）＃3 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ http-foundation \ Session \ Session.php（271）：Symfony \ Component \ HttpFoundation \ Session \ Session-> getBag（'attributes' ）＃4 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ http-foundation \ Session \ Session.php（73）：Symfony \ Component \ HttpFoundation \ Session \ Session-> getAttributeBag（）＃5 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ security \ Http \ Firewall \ ContextListener.php（88）：Symfony \ Component \ HttpFoundation \ Session \ Session-> get（'_ security_main'）＃6 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ security-bundle \ Debug \ WrappedListener.php（46）：Symfony \ Component \ Security \ Http \ Firewall \ ContextListener-> handle（Object（Symfony \ Component \ HttpKernel \ Event \ GetResponseEvent））＃7 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ security-bundle \ Debug \ TraceableFirewallListener.php（35）：Symfony \ Bundle \ SecurityBundle \ Debug \ WrappedListener-> handle（对象（Symfony \ Component \ HttpKernel \ Event \ GetResponseEvent））＃8 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ security \ Http \ Firewall.php（56）：Symfony \ Bundle \ SecurityBundle \ Debug \ TraceableFirewallListener-> handleRequest（Object（Symfony \ Component \ HttpKernel \ Event \ GetResponseEvent），Object（Symfony \ Component \ DependencyInjection \ Argument \ RewindableGenerator））＃9 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ security-bundle \ EventListener \ FirewallListener.php（48）：Symfony \ Component \ Security \ Http \ Firewall-> onKernelRequest（Object（Symfony \ Component \ HttpKernel \ Event \ GetResponseEvent））＃10 [internal func ]：Symfony \ Bundle \ SecurityBundle \ EventListener \ FirewallListener-> onKernelRequest（Object（Symfony \ Component \ HttpKernel \ Event \ GetResponseEvent），'kernel.request'，Object（Symfony \ Component \ HttpKernel \ Debug \ TraceableEventDispatcher））＃11 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ event-dispatcher \ Debug \ WrappedListener.php（104）：call_user_func（Array，Object（Symfony \ Component \ HttpKernel \ Event \ GetResponseEvent），'kernel.request'，Object （Symfony \ Component \ HttpKernel \ Debug \ TraceableEventDispatcher））＃12 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ event-dispatcher \ EventDispatcher.php（212）：Symfony \ Component \ EventDispatcher \ Debug \ WrappedListener - > __ invoke （Object（Symfony \ Component \ HttpKernel \ Event \ GetResponseEvent），'kernel.request'，Object（Symfony \ Component \ EventDispatcher \ EventDispatcher））＃13 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ event-dispatcher \ EventDispatcher.php（44）：Symfony \ Component \ EventDispatcher \ EventDispatcher-> doDispatch（Array，'kernel.request'，Object（Symfony \ Component \ HttpKernel \ Event \ GetRespons） eEvent））＃14 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ event-dispatcher \ Debug \ TraceableEventDispatcher.php（139）：Symfony \ Component \ EventDispatcher \ EventDispatcher-> dispatch（'kernel.request'，Object（ Symfony \ Component \ HttpKernel \ Event \ GetResponseEvent））＃15 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ http-kernel \ HttpKernel.php（125）：Symfony \ Component \ EventDispatcher \ Debug \ TraceableEventDispatcher-> dispatch（ 'kernel.request'，Object（Symfony \ Component \ HttpKernel \ Event \ GetResponseEvent））＃16 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ http-kernel \ HttpKernel.php（66）：Symfony \ Component \ HttpKernel \ HttpKernel-> handleRaw（Object（Symfony \ Component \ HttpFoundation \ Request），1）＃17 C：\ xampp \ htdocs \ Auth \ vendor \ symfony \ http-kernel \ Kernel.php（190）：Symfony \ Component \ HttpKernel \ HttpKernel-> handle（对象（Symfony \ Component \ HttpFoundation \ Request），1，true）＃18 C：\ xampp \ htdocs \ Auth \ public \ index.php（37）：Symfony \ Component \ HttpKernel \ Kernel-> handle（Object（Symfony \ Component \ HttpFoundation \ Request））＃19