Missing Controller Exception after installing FriendsOfCake/cakephp-csvview - php

Question

I installed FriendsOfCake/cakephp-csvview using
php ../composer.phar require friendsofcake/cakephp-csvview:~3.0.
After which all pages show Missing Controller Exception (they were definitely OK), even after commenting out Plugin::load('CsvView') in bootstrap.php. I doubt php was unable to locate the controller class but don't know why. I have used find . -mtime -1, no files under src have changed.
Could anyone please tell me how Cakephp figures out the class file locations so I can troubleshoot?
Stack trace below:
2016-10-04 03:20:39 Warning: Headers already sent in {base}/vendor/cakephp/cakephp/src/Error/Debugger.php:753
2016-10-04 03:20:39 Error: [Cake\Routing\Exception\MissingControllerException] Controller class Holders could not be found.
Exception Attributes: array (
'class' => 'Holders',
'plugin' => false,
'prefix' => false,
'_ext' => false,
)
Request URL: /
Client IP: 127.0.0.1
Stack Trace:
#0 {base}/vendor/cakephp/cakephp/src/Http/ControllerFactory.php(72): Cake\Http\ControllerFactory->missingController(Object(Cake\Network\Request))
#1 {base}/vendor/cakephp/cakephp/src/Routing/Filter/ControllerFactoryFilter.php(63): Cake\Http\ControllerFactory->create(Object(Cake\Network\Request), Object(Cake\Network\Response))
#2 {base}/vendor/cakephp/cakephp/src/Routing/Filter/ControllerFactoryFilter.php(49): Cake\Routing\Filter\ControllerFactoryFilter->_getController(Object(Cake\Network\Request), Object(Cake\Network\Response))
#3 {base}/vendor/cakephp/cakephp/src/Routing/DispatcherFilter.php(144): Cake\Routing\Filter\ControllerFactoryFilter->beforeDispatch(Object(Cake\Event\Event))
#4 {base}/vendor/cakephp/cakephp/src/Event/EventManager.php(426): Cake\Routing\DispatcherFilter->handle(Object(Cake\Event\Event), Object(Cake\Network\Request), Object(Cake\Network\Response))
#5 {base}/vendor/cakephp/cakephp/src/Event/EventManager.php(391): Cake\Event\EventManager->_callListener(Array, Object(Cake\Event\Event))
#6 {base}/vendor/cakephp/cakephp/src/Event/EventDispatcherTrait.php(78): Cake\Event\EventManager->dispatch(Object(Cake\Event\Event))
#7 {base}/vendor/cakephp/cakephp/src/Http/ActionDispatcher.php(81): Cake\Http\ActionDispatcher->dispatchEvent('Dispatcher.befo...', Array)
#8 {base}/vendor/cakephp/cakephp/src/Routing/Dispatcher.php(60): Cake\Http\ActionDispatcher->dispatch(Object(Cake\Network\Request), Object(Cake\Network\Response))
#9 {base}/webroot/index.php(37): Cake\Routing\Dispatcher->dispatch(Object(Cake\Network\Request), Object(Cake\Network\Response))
#10 {main}

Answer 1

If at all, CakePHP only tries to figure fully qualified classnames from shorter ones, it doesn't handle including class files or figuring their locations, as of CakePHP 3 it relies on the composer autoloader (vendor/autoload.php) to do that.
If things broke after updating a dependency, which will also cause the autoloader to be re-dumped, chances are good that the autoloader broke (for whatever reason).