Setting unknown style options is deprecated and will throw an exception in Symfony 4.0.

The QuestionHelper::setInputStream() method is deprecated and will be removed in Symfony 4.0. Use StreamableInputInterface::setStream() or CommandTester::setInputs() instead.

Before:

$input = new ArrayInput();

$questionHelper->setInputStream($stream);
$questionHelper->ask($input, $output, $question);

After:

$input = new ArrayInput();
$input->setStream($stream);

$questionHelper->ask($input, $output, $question);

Before:

$commandTester = new CommandTester($command);

$stream = fopen('php://memory', 'r+', false);
fputs($stream, "AppBundle\nYes");
rewind($stream);

$command->getHelper('question')->setInputStream($stream);

$commandTester->execute();

After:

$commandTester = new CommandTester($command);

$commandTester->setInputs(array('AppBundle', 'Yes'));

$commandTester->execute();

Calling get() on a ContainerBuilder instance before compiling the container is deprecated and will throw an exception in Symfony 4.0.

Setting or unsetting a private service with the Container::set() method is deprecated. Only public services can be set or unset in Symfony 4.0.

Checking the existence of a private service with the Container::has() method is deprecated and will return false in Symfony 4.0.

Requesting a private service with the Container::get() method is deprecated and will no longer be supported in Symfony 4.0.

Calling isValid() on a Form instance before submitting it is deprecated and will throw an exception in Symfony 4.0.

Before:

if ($form->isValid()) {
    // ...
}

After:

if ($form->isSubmitted() && $form->isValid()) {
    // ...
}

Extending the following methods of Response is deprecated (these methods will be final in 4.0):

• setDate/getDate
• setExpires/getExpires
• setLastModified/getLastModified
• setProtocolVersion/getProtocolVersion
• setStatusCode/getStatusCode
• setCharset/getCharset
• setPrivate/setPublic
• getAge
• getMaxAge/setMaxAge
• setSharedMaxAge
• getTtl/setTtl
• setClientTtl
• getEtag/setEtag
• hasVary/getVary/setVary
• isInvalid/isSuccessful/isRedirection/isClientError/isServerError
• isOk/isForbidden/isNotFound/isRedirect/isEmpty

Checking only for cacheable HTTP methods with Request::isMethodSafe() is deprecated since version 3.2 and will throw an exception in 4.0. Disable checking only for cacheable methods by calling the method with false as first argument or use Request::isMethodCacheable() instead.

DataCollector::varToString() is deprecated and will be removed in Symfony 4.0. Use the cloneVar() method instead.

Surrogate name in a Surrogate-Capability HTTP request header has been changed to 'symfony'.

Before:

Surrogate-Capability: symfony2="ESI/1.0"

After:

Surrogate-Capability: symfony="ESI/1.0"

Injecting the Form TwigRenderer into the FormExtension is deprecated and has no more effect. Upgrade Twig to ^1.30, inject the Twig_Environment into the TwigRendererEngine and load the TwigRenderer using the Twig_FactoryRuntimeLoader instead.

Before:

use Symfony\Bridge\Twig\Extension\FormExtension;
use Symfony\Bridge\Twig\Form\TwigRenderer;
use Symfony\Bridge\Twig\Form\TwigRendererEngine;

// ...
$rendererEngine = new TwigRendererEngine(array('form_div_layout.html.twig'));
$rendererEngine->setEnvironment($twig);
$twig->addExtension(new FormExtension(new TwigRenderer($rendererEngine, $csrfTokenManager)));

After:

$rendererEngine = new TwigRendererEngine(array('form_div_layout.html.twig'), $twig);
$twig->addRuntimeLoader(new \Twig_FactoryRuntimeLoader(array(
    TwigRenderer::class => function () use ($rendererEngine, $csrfTokenManager) {
        return new TwigRenderer($rendererEngine, $csrfTokenManager);
    },
)));
$twig->addExtension(new FormExtension());

Deprecated the TwigRendererEngineInterface interface, it will be removed in 4.0.

Tests\Constraints\AbstractConstraintValidatorTest has been deprecated in favor of Test\ConstraintValidatorTestCase.

Before:

// ...
use Symfony\Component\Validator\Tests\Constraints\AbstractConstraintValidatorTest;

class MyCustomValidatorTest extends AbstractConstraintValidatorTest
{
    // ...
}

After:

// ...
use Symfony\Component\Validator\Test\ConstraintValidatorTestCase;

class MyCustomValidatorTest extends ConstraintValidatorTestCase
{
    // ...
}

Setting the strict option of the Choice Constraint to false has been deprecated and the option will be changed to true as of 4.0.

// ...
use Symfony\Component\Validator\Constraints as Assert;

class MyEntity
{
    /**
     * @Assert\Choice(choices={"MR", "MRS"}, strict=true)
     */
    private $salutation;
}

Support for silently ignoring duplicate mapping keys in YAML has been deprecated and will lead to a ParseException in Symfony 4.0.

Mappings with a colon (:) that is not followed by a whitespace are deprecated and will lead to a ParseException in Symfony 4.0 (e.g. foo:bar must be foo: bar).