Fatal error: Cannot redeclare class Symfony\Component\EventDispatcher\Event in POST requests

[stollr]

Since I have installed FOSHttpCacheBundle I get a strange error on POST requests (when submitting any form):

Fatal error: Cannot redeclare class Symfony\Component\EventDispatcher\Event in C:\projects\acme\app\cache\dev\classes.php on line 2136

Call Stack:
    0.0020     136568   1. {main}() C:\projects\acme\web\app_dev.php:0
    0.0380    1908496   2. FOS\HttpCacheBundle\SymfonyCache\EventDispatchingHttpCache->handle() C:\projects\acme\web\app_dev.php:34
    0.0380    1908952   3. Symfony\Component\HttpKernel\HttpCache\HttpCache->handle() C:\projects\acme\vendor\friendsofsymfony\http-cache-bundle\SymfonyCache\EventDispatchingHttpCache.php:122
    0.0390    1928528   4. FOS\HttpCacheBundle\SymfonyCache\EventDispatchingHttpCache->invalidate() C:\projects\acme\vendor\symfony\symfony\src\Symfony\Component\HttpKernel\HttpCache\HttpCache.php:206
    0.0410    1948712   5. Symfony\Component\HttpKernel\HttpCache\HttpCache->invalidate() C:\projects\acme\vendor\friendsofsymfony\http-cache-bundle\SymfonyCache\EventDispatchingHttpCache.php:161
    0.0410    1948736   6. Symfony\Component\HttpKernel\HttpCache\HttpCache->pass() C:\projects\acme\vendor\symfony\symfony\src\Symfony\Component\HttpKernel\HttpCache\HttpCache.php:275
    0.0410    1949016   7. Symfony\Bundle\FrameworkBundle\HttpCache\HttpCache->forward() C:\projects\acme\vendor\symfony\symfony\src\Symfony\Component\HttpKernel\HttpCache\HttpCache.php:258
    0.0410    1949176   8. Symfony\Component\HttpKernel\Kernel->boot() C:\projects\acme\vendor\symfony\symfony\src\Symfony\Bundle\FrameworkBundle\HttpCache\HttpCache.php:56
    0.0410    1949240   9. Symfony\Component\HttpKernel\Kernel->doLoadClassCache() C:\projects\acme\app\bootstrap.php.cache:2408
    0.0430    2034240  10. Symfony\Component\ClassLoader\ClassCollectionLoader::load() C:\projects\acme\app\bootstrap.php.cache:2573
    0.1000    4173632  11. require_once('C:\projects\acme\app\cache\dev\classes.php') C:\projects\acme\vendor\symfony\symfony\src\Symfony\Component\ClassLoader\ClassCollectionLoader.php:91

Now, when I delete the cache folder via filesystem (not with app/console cache:clear) the next POST request works, but all next POST requests are failing again with the same error message.
But when I execute app/console cache:clear after removing the cache folder it seem to work on all requests.

I have already figured out that on POST requests the Symfony\Component\EventDispatcher\Event class is loaded via autoloading when an instance of CacheEvent is created in FOS\HttpCacheBundle\SymfonyCache\EventDispatchingHttpCache::invalidate. Later the Symfony HttpKernel boots and loads the class cache (the classes.php in the cache folder) which contains the Event class, too. This results in the mentioned redeclaration error.

What confuses me, is that the Event class is not compiled into classes.php when app/console cache:clear is executed after removing the cache folder.

Does anyone has a clue about this issue?

[dbu]

How does your web/app.php file look? mine starts like this:

use Symfony\Component\HttpFoundation\Request;

$loader = require_once __DIR__.'/../app/bootstrap.php.cache';

require_once __DIR__.'/../app/AppKernel.php';

could it be that you load the AppKernel before loading bootstrap.php.cache? or do something else before loading the bootstrap?

[stof]

@dbu it is not about app/bootstrap.php.cache, but about app/cache/dev/classes.php, which is loaded by $kernel->loadClassCache() (or something like that, I'm not sure about the method name), which loads the file generated based on classes that bundles are asking to aggregate together.

[stollr]

@dbu My app.php looks similar to yours. stof is right. The problem is the classes.php which is mentioned in my PRs.
And afaik this issue only occures if you are using Symfony's cache with cache invalidation enabled.

[dbu]

i did not know that thing even existed :-O got it now. thanks for working on the fix!

[ddeboer]

@dbu This seems quite a nasty bug. Do you have any idea why our tests didn’t catch it?

[dbu]

because it has to do with caching, we probably dont trigger that case.

[dbu]

this will be fixed in FriendsOfSymfony/FOSHttpCache#249

the workaround for now is to do a class_exists('FOS\\HttpCache\\SymfonyCache\\CacheEvent') at the beginning of AppKernel::handle, and in app/console if the console uses the class cache mechanism of the kernel.