After my first impressions with Magento 2, here are my second impressions:

A fully working and sound Magento 2.0, broke overnight, on its second day, with not even a single products uploaded. It showed something similar to:

There has been an error processing your request

Exception printing is disabled by default for security reasons.

Error log record number: 875623260970

You may think its fun, but in a full installation of over 60,000 files its a pain to find how to find the log and debug. BTW, here is a hint, it was not recorded in any of the log files. All log files were clean.

If by any chance you succeed to find how to enable the error log, you will get something similar to this:

Class Magento\Framework\View\Layout\ReaderPool does not exist
#0 /web/remiya.com/vendor/magento/framework/ObjectManager/Definition/Runtime.php(44): Magento\Framework\Code\Reader\ClassReader->getConstructor('Magento\\Framewo...')
#1 /web/remiya.com/vendor/magento/framework/ObjectManager/Factory/Dynamic/Developer.php(71): Magento\Framework\ObjectManager\Definition\Runtime->getParameters('Magento\\Framewo...')
#2 /web/remiya.com/vendor/magento/framework/ObjectManager/ObjectManager.php(71): Magento\Framework\ObjectManager\Factory\Dynamic\Developer->create('Magento\\Framewo...')
#3 /web/remiya.com/vendor/magento/framework/ObjectManager/Factory/AbstractFactory.php(236): Magento\Framework\ObjectManager\ObjectManager->get('Magento\\Framewo...')
#4 /web/remiya.com/vendor/magento/framework/ObjectManager/Factory/Dynamic/Developer.php(53): Magento\Framework\ObjectManager\Factory\AbstractFactory->resolveArgument(Array, 'Magento\\Framewo...', NULL, 'layout', 'Magento\\Framewo...')
#5 /web/remiya.com/vendor/magento/framework/ObjectManager/Factory/Dynamic/Developer.php(82): Magento\Framework\ObjectManager\Factory\Dynamic\Developer->_resolveArguments('Magento\\Framewo...', Array, Array)
#6 /web/remiya.com/vendor/magento/framework/ObjectManager/ObjectManager.php(71): Magento\Framework\ObjectManager\Factory\Dynamic\Developer->create('Magento\\Framewo...')
#7 /web/remiya.com/vendor/magento/framework/ObjectManager/Factory/AbstractFactory.php(236): Magento\Framework\ObjectManager\ObjectManager->get('Magento\\Framewo...')
#8 /web/remiya.com/vendor/magento/framework/ObjectManager/Factory/Dynamic/Developer.php(53): Magento\Framework\ObjectManager\Factory\AbstractFactory->resolveArgument(Array, 'Magento\\Framewo...', NULL, 'view', 'Magento\\Framewo...')
#9 /web/remiya.com/vendor/magento/framework/ObjectManager/Factory/Dynamic/Developer.php(82): Magento\Framework\ObjectManager\Factory\Dynamic\Developer->_resolveArguments('Magento\\Framewo...', Array, Array)
#10 /web/remiya.com/vendor/magento/framework/ObjectManager/ObjectManager.php(71): Magento\Framework\ObjectManager\Factory\Dynamic\Developer->create('Magento\\Framewo...')
#11 /web/remiya.com/vendor/magento/framework/ObjectManager/Factory/AbstractFactory.php(236): Magento\Framework\ObjectManager\ObjectManager->get('Magento\\Framewo...')
#12 /web/remiya.com/vendor/magento/framework/ObjectManager/Factory/Dynamic/Developer.php(53): Magento\Framework\ObjectManager\Factory\AbstractFactory->resolveArgument(Array, 'Magento\\Framewo...', NULL, 'context', 'Magento\\Cms\\Con...')
#13 /web/remiya.com/vendor/magento/framework/ObjectManager/Factory/Dynamic/Developer.php(82): Magento\Framework\ObjectManager\Factory\Dynamic\Developer->_resolveArguments('Magento\\Cms\\Con...', Array, Array)
#14 /web/remiya.com/vendor/magento/framework/ObjectManager/ObjectManager.php(57): Magento\Framework\ObjectManager\Factory\Dynamic\Developer->create('Magento\\Cms\\Con...', Array)
#15 /web/remiya.com/vendor/magento/framework/App/ActionFactory.php(37): Magento\Framework\ObjectManager\ObjectManager->create('Magento\\Cms\\Con...')
#16 /web/remiya.com/vendor/magento/framework/App/Router/Base.php(300): Magento\Framework\App\ActionFactory->create('Magento\\Cms\\Con...')
#17 /web/remiya.com/vendor/magento/framework/App/Router/Base.php(161): Magento\Framework\App\Router\Base->matchAction(Object(Magento\Framework\App\Request\Http), Array)
#18 /web/remiya.com/vendor/magento/framework/App/FrontController.php(50): Magento\Framework\App\Router\Base->match(Object(Magento\Framework\App\Request\Http))
#19 [internal function]: Magento\Framework\App\FrontController->dispatch(Object(Magento\Framework\App\Request\Http))
#20 /web/remiya.com/vendor/magento/framework/Interception/Interceptor.php(74): call_user_func_array(Array, Array)
#21 /web/remiya.com/vendor/magento/framework/Interception/Chain/Chain.php(70): Magento\Framework\App\FrontController\Interceptor->___callParent('dispatch', Array)
#22 /web/remiya.com/vendor/magento/framework/Interception/Chain/Chain.php(63): Magento\Framework\Interception\Chain\Chain->invoke_next('Magento\\Framewo...', 'dispatch', Object(Magento\Framework\App\FrontController\Interceptor), Array, 'requestPreproce...')
#23 /web/remiya.com/vendor/magento/module-store/App/FrontController/Plugin/RequestPreprocessor.php(89): Magento\Framework\Interception\Chain\Chain->Magento\Framework\Interception\Chain\{closure}(Object(Magento\Framework\App\Request\Http))
#24 [internal function]: Magento\Store\App\FrontController\Plugin\RequestPreprocessor->aroundDispatch(Object(Magento\Framework\App\FrontController\Interceptor), Object(Closure), Object(Magento\Framework\App\Request\Http))
#25 /web/remiya.com/vendor/magento/framework/Interception/Chain/Chain.php(67): call_user_func_array(Array, Array)
#26 /web/remiya.com/vendor/magento/framework/Interception/Chain/Chain.php(63): Magento\Framework\Interception\Chain\Chain->invoke_next('Magento\\Framewo...', 'dispatch', Object(Magento\Framework\App\FrontController\Interceptor), Array, 'install')
#27 /web/remiya.com/vendor/magento/framework/Module/Plugin/DbStatusValidator.php(69): Magento\Framework\Interception\Chain\Chain->Magento\Framework\Interception\Chain\{closure}(Object(Magento\Framework\App\Request\Http))
#28 [internal function]: Magento\Framework\Module\Plugin\DbStatusValidator->aroundDispatch(Object(Magento\Framework\App\FrontController\Interceptor), Object(Closure), Object(Magento\Framework\App\Request\Http))
#29 /web/remiya.com/vendor/magento/framework/Interception/Chain/Chain.php(67): call_user_func_array(Array, Array)
#30 /web/remiya.com/vendor/magento/framework/Interception/Chain/Chain.php(63): Magento\Framework\Interception\Chain\Chain->invoke_next('Magento\\Framewo...', 'dispatch', Object(Magento\Framework\App\FrontController\Interceptor), Array, 'front-controlle...')
#31 /web/remiya.com/vendor/magento/module-page-cache/Model/App/FrontController/VarnishPlugin.php(55): Magento\Framework\Interception\Chain\Chain->Magento\Framework\Interception\Chain\{closure}(Object(Magento\Framework\App\Request\Http))
#32 [internal function]: Magento\PageCache\Model\App\FrontController\VarnishPlugin->aroundDispatch(Object(Magento\Framework\App\FrontController\Interceptor), Object(Closure), Object(Magento\Framework\App\Request\Http))
#33 /web/remiya.com/vendor/magento/framework/Interception/Chain/Chain.php(67): call_user_func_array(Array, Array)
#34 /web/remiya.com/vendor/magento/framework/Interception/Interceptor.php(136): Magento\Framework\Interception\Chain\Chain->invoke_next('Magento\\Framewo...', 'dispatch', Object(Magento\Framework\App\FrontController\Interceptor), Array, 'front-controlle...')
#35 /web/remiya.com/vendor/magento/module-page-cache/Model/App/FrontController/BuiltinPlugin.php(73): Magento\Framework\App\FrontController\Interceptor->Magento\Framework\Interception\{closure}(Object(Magento\Framework\App\Request\Http))
#36 [internal function]: Magento\PageCache\Model\App\FrontController\BuiltinPlugin->aroundDispatch(Object(Magento\Framework\App\FrontController\Interceptor), Object(Closure), Object(Magento\Framework\App\Request\Http))
#37 /web/remiya.com/vendor/magento/framework/Interception/Interceptor.php(140): call_user_func_array(Array, Array)
#38 /web/remiya.com/var/generation/Magento/Framework/App/FrontController/Interceptor.php(26): Magento\Framework\App\FrontController\Interceptor->___callPlugins('dispatch', Array, Array)
#39 /web/remiya.com/vendor/magento/framework/App/Http.php(115): Magento\Framework\App\FrontController\Interceptor->dispatch(Object(Magento\Framework\App\Request\Http))
#40 /web/remiya.com/vendor/magento/framework/App/Bootstrap.php(258): Magento\Framework\App\Http->launch()
#41 /web/remiya.com/index.php(39): Magento\Framework\App\Bootstrap->run(Object(Magento\Framework\App\Http))
#42 {main}

How a working file can disappear overnight from a folder that never gets used, is beyound belief.

Well, you may suppose, if you do a "composer update" the dependencies will be downloaded again.

composer update

Loading composer repositories with package informa Authentication required (repo.magento.com):

  Username: *********

  Password: **********

[Composer\Downloader\TransportException]

Invalid credentials for 'https://repo.magento.com/packages.json', aborting.

Why an open source software would require username and password to download dependencies?

In summary, Magento 2.0, is a big step backwards. Its initial release with 40,000 files is now 60,000 after the second release ver. 2.0.2. Much dissappointed.

PS. 60,000 files to show a couple of products :(