Symfony 4 registration form second submit "There is already an active transaction"

Question

I have created a user registry just as in the documentation. At some point later I wanted to add the CSRF. Since then it does not work properly anymore. I have the package installed and removed. https://symfony.com/doc/current/doctrine/registration_form.html

composer require security-csrf
composer remove security-csrf
rm -rf vendor
rm -rf var/cache/*

That did not help.

When I fill out the form and submit. If the user is saved. I do a second time, I get the error message below.

Only when I remove the cookie "PHPSESSID" in the browser, then I can send the form once again. After that is the same problem again.

PDOException:
There is already an active transaction

  at vendor/doctrine/dbal/lib/Doctrine/DBAL/Connection.php:1249
  at PDO->beginTransaction()
     (vendor/doctrine/dbal/lib/Doctrine/DBAL/Connection.php:1249)
  at Doctrine\DBAL\Connection->beginTransaction()
     (vendor/doctrine/orm/lib/Doctrine/ORM/UnitOfWork.php:376)
  at Doctrine\ORM\UnitOfWork->commit(null)
     (vendor/doctrine/orm/lib/Doctrine/ORM/EntityManager.php:358)
  at Doctrine\ORM\EntityManager->flush()
     (src/Controller/RegistrationController.php:40)
  at App\Controller\RegistrationController->registerAction(object(Request), object(UserPasswordEncoder))
     (vendor/symfony/http-kernel/HttpKernel.php:149)
  at Symfony\Component\HttpKernel\HttpKernel->handleRaw(object(Request), 1)
     (vendor/symfony/http-kernel/HttpKernel.php:66)
  at Symfony\Component\HttpKernel\HttpKernel->handle(object(Request), 1, true)
     (vendor/symfony/http-kernel/Kernel.php:190)
  at Symfony\Component\HttpKernel\Kernel->handle(object(Request))
     (public/index.php:37)

I tried to debug that. The transaction was activated somewhere, then not again. I can not find the problem. Is anyone able to help me?

symfony/config/services.yaml

services:
    Symfony\Component\HttpFoundation\Session\Storage\Handler\PdoSessionHandler:
        arguments:
            - !service { class: PDO, factory: 'database_connection:getWrappedConnection' }
            - { db_table: session, db_username: username, db_password: password }

Answer 1

I've had this same issue recently, and for me it was down to using PDOSessionHandler along with sharing the Doctrine connection with getWrappedConnection.

In your services.yaml change your PdoSessionHandler service definition

Symfony\Component\HttpFoundation\Session\Storage\Handler\PdoSessionHandler:
    arguments:
        - !service { class: PDO, factory: 'database_connection:getWrappedConnection' }
        - { lock_mode: 1 }`

I.e. just add the lock_mode argument in addition. That "fixed" it for me, though I'm looking in more depth as to why as it would be better to use LOCK_TRANSACTIONAL rather than LOCK_ADVISORY.