Yii2: Captcha: Could not load the image.

[shi-yang]

What steps will reproduce the problem?

Controller

class SiteController extends Controller
{
    ...
    public function actions()
    {
        return [
            'error' => [
                'class' => 'yii\web\ErrorAction',
            ],
            'captcha' => [
                'class' => 'yii\captcha\CaptchaAction',
                'fixedVerifyCode' => YII_ENV_TEST ? 'testme' : null,
            ],
        ];
    }
    ...
}

Model

class SignupForm extends Model
{
    public $username;
    public $email;
    public $password;
    public $captcha;

    /**
     * @inheritdoc
     */
    public function rules()
    {
        return [
        ...
            ['captcha', 'captcha']
        ...
        ];
    }
}

View

<?= $form->field($model, 'captcha')->widget(\yii\captcha\Captcha::classname(), [
    // configure additional widget properties here
]) ?>

What is the expected result?

Load the image.

What do you get instead?

In my program, Captcha can be displayed properly on some computers, but there are some computers can not be loaded properly, and the browser will appear "Could not load the image".

The same computer, download and install "Yii 2 Basic Application Template" can be displayed, but not in my program.

Additional info

I searched the Internet. If the output buffer is not empty, you can not load the image.The solution is to empty the output buffer before output captcha.
For example, in [[\yii\captcha\CaptchaAction::run()]]

        } else {
            ob_clean();  //Add this line, can solve this problem. Or add in other suitable places
            $this->setHttpHeaders();
            Yii::$app->response->format = Response::FORMAT_RAW;
            return $this->renderImage($this->getVerifyCode());
        }

| Q | A |
| --- | --- |
| Yii version | 2.0.x |
| PHP version | 7.0.4-7ubuntu2.1 |
| Operating system | ubuntu 16.04 |

_Is it a bug?_

[samdark]

Do you know how to reproduce the issue?

[ivanmota]

On those machine that you can't load the image, please check if the user that is runnig the php have the right permission on the directory sessions.save_path or try to save the session on database

[zeevy]

some times may be due to "enableStrictParsing" is set to true and you don't have any url rule for captcha

[samdark]

I see no way to reproduce it so we can't fix it. Closing.

[samatic]

I had same issue and ob_clean() solved it (yii 2.0.9). Thanks @shi-yang.

[shannlove]

I had same issue and ob_clean() solved it. Thanks @shi-yang.

[samdark]

@shannlove any idea how to reproduce it?

[nageennayak11]

Very good @shi-yang, its working for me.
i was tired but now relax.
thank you.

[daliha]

@samatic @nageennayak11
Where did you put ob_clean() to solve the problem?

[samatic]

@daliha look at @shi-yang comment above

[nageennayak11]

https://stackoverflow.com/questions/48017676/yii2-captcha-image-not-showing

or

please change in \vendor\yiisoft\yii2\captcha\CaptchaAction.php and will show image.

[daliha]

@samatic Yesss ... thank you.

[daliha]

@nageennayak11 Thank you

[neoacevedo]

It was working for a long time to me, but suddenly it let to work, and the solution given here is not working in my case.

I set _ob_clean()_ in CaptchaAction and not worked.

It happened just after run composer update.

I run both in my own PC and in AWS Elastic Beanstalk. In both was working, but just today it failed.

I think is beyond Yii and more related with session. Sometimes the sessions cannot be written and that's the actual issue.

[OmgDef]

Super weird, but I faced the same issue on one of my servers on PHP 7.1. Adding ob_clean() to the CaptchaAction class solved the issue. Yii version is 2.0.14. Checked all the permissions for sessions. PHP-FPM can write session files. No errors and warnings in the logs too.

[shi-yang]

@samdark the issue can be reproduce by follwing step:

1. run composer create-project --prefer-dist --stability=dev yiisoft/yii2-app-basic basic to install yii2-app-basic project.

2. add a blank line on config/db.php as below:

<?php
return [
    'class' => 'yii\db\Connection',
    'dsn' => 'mysql:host=localhost;dbname=test',
    'username' => 'root',
    'password' => '123456',
    'charset' => 'utf8'
];

Note: There is a blank line at the beginning of the file

1. Access the application through the following URL:

http://localhost/basic/web/index.php?r=site/contact

[samdark]

Well, that is expected. PHP files should never start with blank lines or BOM else you'll have broken HTTP headers and unexpected input.

[751836594]

I had same issue but I set ob_clean() in CaptchaAction and not worked.
because i don't have permission to write session file