Multiple AppKernel class

[fradnetcom]

After update Symfony 2.8 to 3.x i get this error

PHP Fatal error:  Class 'AppKernel' not found in /var/www/example_project/bin/console on line 27
PHP Stack trace:
PHP   1. {main}() /var/www/example_project/bin/console:0
PHP Fatal error:  Cannot redeclare class AppKernel in /var/www/example_project/vendor/helios-ag/fm-elfinder-bundle/Tests/Functional/AppKernel.php on line 23
PHP Stack trace:
PHP   1. {main}() /var/www/example_project/bin/console:0
PHP   2. Symfony\Component\Debug\ErrorHandler::handleFatalError() /var/www/example_project/vendor/symfony/symfony/src/Symfony/Component/Debug/ErrorHandler.php:0
PHP   3. Symfony\Component\Debug\ErrorHandler->handleException() /var/www/example_project/vendor/symfony/symfony/src/Symfony/Component/Debug/ErrorHandler.php:621
PHP   4. Symfony\Component\Debug\FatalErrorHandler\ClassNotFoundFatalErrorHandler->handleError() /var/www/example_project/vendor/symfony/symfony/src/Symfony/Component/Debug/ErrorHandler.php:549
PHP   5. Symfony\Component\Debug\FatalErrorHandler\ClassNotFoundFatalErrorHandler->getClassCandidates() /var/www/example_project/vendor/symfony/symfony/src/Symfony/Component/Debug/FatalErrorHandler/ClassNotFoundFatalErrorHandler.php:62
PHP   6. Symfony\Component\Debug\FatalErrorHandler\ClassNotFoundFatalErrorHandler->findClassInPath() /var/www/example_project/vendor/symfony/symfony/src/Symfony/Component/Debug/FatalErrorHandler/ClassNotFoundFatalErrorHandler.php:118
PHP   7. Symfony\Component\Debug\FatalErrorHandler\ClassNotFoundFatalErrorHandler->convertFileToClass() /var/www/example_project/vendor/symfony/symfony/src/Symfony/Component/Debug/FatalErrorHandler/ClassNotFoundFatalErrorHandler.php:143
Script Sensio\Bundle\DistributionBundle\Composer\ScriptHandler::clearCache handling the post-update-cmd event terminated with an exception                                                                                                                                                                                                          
  [RuntimeException]                                                                                                                                                                                      
  An error occurred when executing the "'cache:clear --no-warmup'" command:                                                                                                                               
  PHP Fatal error:  Class 'AppKernel' not found in /var/www/example_project/bin/console on line 27                                                                                                         
  PHP Stack trace:                                                                                                                                                                                        
  PHP   1. {main}() /var/www/example_project/bin/console:0                                                                                                                                                 
  PHP Fatal error:  Cannot redeclare class AppKernel in /var/www/example_project/vendor/helios-ag/fm-elfinder-bundle/Tests/Functional/AppKernel.php on line 23                                             
  PHP Stack trace:                                                                                                                                                                                        
  PHP   1. {main}() /var/www/example_project/bin/console:0                                                                                                                                                 
  PHP   2. Symfony\Component\Debug\ErrorHandler::handleFatalError() /var/www/example_projectvendor/symfony/symfony/src/Symfony/Component/Debug/ErrorHandler.php:0                                         
  PHP   3. Symfony\Component\Debug\ErrorHandler->handleException() /var/www/example_project/vendor/symfony/symfony/src/Symfony/Component/Debug/ErrorHandler.php:621                                        
  PHP   4. Symfony\Component\Debug\FatalErrorHandler\ClassNotFoundFatalErrorHandler->handleError() /var/www/example_project/vendor/symfony/symfony/src/Symfony/Component/Debug/ErrorHandler.php:549        
  PHP   5. Symfony\Component\Debug\FatalErrorHandler\ClassNotFoundFatalErrorHandler->getClassCandidates() /var/www/example_project/vendor/symfony/symfony/src/Symfony/Component/Debug/FatalErrorHandler/C  
  lassNotFoundFatalErrorHandler.php:62                                                                                                                                                                    
  PHP   6. Symfony\Component\Debug\FatalErrorHandler\ClassNotFoundFatalErrorHandler->findClassInPath() /var/www/example_project/vendor/symfony/symfony/src/Symfony/Component/Debug/FatalErrorHandler/Clas  
  sNotFoundFatalErrorHandler.php:118                                                                                                                                                                      
  PHP   7. Symfony\Component\Debug\FatalErrorHandler\ClassNotFoundFatalErrorHandler->convertFileToClass() /var/www/example_project/vendor/symfony/symfony/src/Symfony/Component/Debug/FatalErrorHandler/C  
  lassNotFoundFatalErrorHandler.php:143

Some solution how fix this ?

[helios-ag]

@fradnetcom can you share (on gist) your whole composer.json please

[fradnetcom]

I solved problem - in old version don't have in composer classmap:

"autoload": {
        "psr-4": {
            "": "src/"
        },
        "classmap": [
            "app/AppKernel.php",
            "app/AppCache.php"
        ]
    },

Now is workin ok.