Exception: Deprecated Functionality: strpos(): Passing null to parameter #1 ($haystack) of type string is deprecated in /var/www/testwebkeller/vendor/magento/framework/Filesystem/Driver/File.php on line 878 in /var/www/testwebkeller/vendor/magento/framework/App/ErrorHandler.php:61
Stack trace:
#0 [internal function]: Magento\Framework\App\ErrorHandler->handler()
#1 /var/www/testwebkeller/vendor/magento/framework/Filesystem/Driver/File.php(878): strpos()
#2 /var/www/testwebkeller/vendor/magento/framework/Filesystem/Directory/Read.php(113): Magento\Framework\Filesystem\Driver\File->getAbsolutePath()
#3 /var/www/testwebkeller/vendor/magento/framework/App/Cache/Frontend/Factory.php(126): Magento\Framework\Filesystem\Directory\Read->getAbsolutePath()
#4 /var/www/testwebkeller/vendor/magento/framework/App/Cache/Frontend/Pool.php(69): Magento\Framework\App\Cache\Frontend\Factory->create()
#5 /var/www/testwebkeller/vendor/magento/framework/App/Cache/Frontend/Pool.php(151): Magento\Framework\App\Cache\Frontend\Pool->_initialize()
#6 /var/www/testwebkeller/vendor/magento/framework/App/Cache/Type/FrontendPool.php(87): Magento\Framework\App\Cache\Frontend\Pool->get()
#7 /var/www/testwebkeller/vendor/magento/framework/App/Cache/Type/Config.php(49): Magento\Framework\App\Cache\Type\FrontendPool->get()
#8 /var/www/testwebkeller/vendor/magento/framework/Cache/Frontend/Decorator/Bare.php(65): Magento\Framework\App\Cache\Type\Config->_getFrontend()
#9 /var/www/testwebkeller/vendor/magento/framework/Interception/PluginList/PluginList.php(288): Magento\Framework\Cache\Frontend\Decorator\Bare->load()
#10 /var/www/testwebkeller/vendor/magento/framework/Interception/PluginList/PluginList.php(266): Magento\Framework\Interception\PluginList\PluginList->_loadScopedData()
#11 /var/www/testwebkeller/generated/code/Magento/Framework/App/Http/Interceptor.php(35): Magento\Framework\Interception\PluginList\PluginList->getNext()
#12 /var/www/testwebkeller/vendor/magento/framework/App/Bootstrap.php(267): Magento\Framework\App\Http\Interceptor->catchException()
#13 /var/www/testwebkeller/pub/index.php(73): Magento\Framework\App\Bootstrap->run()
#14 {main}