Probleme de connexion admin

[Misterkfr]

Bonjour , m'a page admin me fais ERROR 500 comment puis-je faire cordialement 

[Misterkfr]

RuntimeException in PhpDumper.php line 1403:Cannot dump definition because of invalid class name (NULL)

in PhpDumper.php line 1403

at PhpDumper->dumpLiteralClass('NULL') in PhpDumper.php line 790

at PhpDumper->addNewInstance('_defaults', object(Definition), 'return ', '$this->services['_defaults'] = ') in PhpDumper.php line 394

at PhpDumper->addServiceInstance('_defaults', object(Definition)) in PhpDumper.php line 639

at PhpDumper->addService('_defaults', object(Definition)) in PhpDumper.php line 666

at PhpDumper->addServices() in PhpDumper.php line 145

at PhpDumper->dump(array('class' => 'appDevDebugProjectContainer', 'base_class' => 'Container', 'namespace' => '', 'debug' => true, 'file' => '/home/rinkoksh/www/app/cache/dev/appDevDebugProjectContainer.php')) in bootstrap.php.cache line 2846

at Kernel->dumpContainer(object(ConfigCache), object(ContainerBuilder), 'appDevDebugProjectContainer', 'Container') in bootstrap.php.cache line 2759

at Kernel->initializeContainer() in bootstrap.php.cache line 2533

at Kernel->boot() in bootstrap.php.cache line 2564

at Kernel->handle(object(Request), '1', false) in index.php line 86