Attempted to call an undefined method named "setMiddlewares" of class "Doctrine\DBAL\Configuration".

[SteppingHat]

I've just updated to 2.6 and received the following error.
I have absolutely no clue what the problem is. I've tried basic troubleshooting (removing vendor directory and doing a fresh install, clearing cache, etc.), but all I know is that reverting back to 2.5.7 resolved the issue for me.

Symfony\Component\ErrorHandler\Error\UndefinedMethodError:
Attempted to call an undefined method named "setMiddlewares" of class "Doctrine\DBAL\Configuration".

  at /app/var/cache/dev/ContainerFcqqLxB/App_KernelDevDebugContainer.php:2784
  at ContainerFcqqLxB\App_KernelDevDebugContainer->getDoctrine_Dbal_DefaultConnectionService()
     (/app/var/cache/dev/ContainerFcqqLxB/App_KernelDevDebugContainer.php:2865)
  at ContainerFcqqLxB\App_KernelDevDebugContainer->getDoctrine_Orm_DefaultEntityManagerService()
     (/app/var/cache/dev/ContainerFcqqLxB/App_KernelDevDebugContainer.php:15396)
  at ContainerFcqqLxB\App_KernelDevDebugContainer->getValidator_BuilderService()
     (/app/var/cache/dev/ContainerFcqqLxB/App_KernelDevDebugContainer.php:15440)
  at ContainerFcqqLxB\App_KernelDevDebugContainer->getValidator_Mapping_CacheWarmerService()
     (/app/var/cache/dev/ContainerFcqqLxB/App_KernelDevDebugContainer.php:2353)
  at ContainerFcqqLxB\App_KernelDevDebugContainer->ContainerFcqqLxB\{closure}()
     (/app/vendor/symfony/http-kernel/CacheWarmer/CacheWarmerAggregate.php:91)
  at Symfony\Component\HttpKernel\CacheWarmer\CacheWarmerAggregate->warmUp('/app/var/cache/dev')
     (/app/vendor/symfony/http-kernel/Kernel.php:587)
  at Symfony\Component\HttpKernel\Kernel->initializeContainer()
     (/app/vendor/symfony/http-kernel/Kernel.php:789)
  at Symfony\Component\HttpKernel\Kernel->preBoot()
     (/app/vendor/symfony/http-kernel/Kernel.php:190)
  at Symfony\Component\HttpKernel\Kernel->handle(object(Request))
     (/app/public/index.php:25)   

(Sorry for the vague description, I didn't know what else I can provide. If you need anything else from me, please ask!)

[dmaicher]

See #1485