Magento installation fails due to redis socket open error

Question

I'm new to Magento and trying to install for the first time. However during the installation I get this weird error:

Module 'Magento_WishlistSampleData':

DDL cache cleared successfully

Installing user configuration...
[ERROR] exception 'Exception' with message 'Warning: SessionHandler::read(): open(unix:///data/sockets/databases/redis/redis.sock?persistent=1&weight=1&database=0&prefix=PHPREDIS_SESSION-abcd-/sess_42tt4f3ppg1ql8i7kppad25225, O_RDWR) failed: No such file or directory (2) in /data/web/abcd/html/verlag_2.19/vendor/magento/framework/Session/SaveHandler/Native.php on line 22' in /data/web/abcd/html/verlag_2.19/vendor/magento/framework/App/ErrorHandler.php:61
Stack trace:
#0 [internal function]: Magento\Framework\App\ErrorHandler->handler(2, 'SessionHandler:...', '/data/web/abc...', 22, Array)
#1 /data/web/abcd/html/verlag_2.19/vendor/magento/framework/Session/SaveHandler/Native.php(22): SessionHandler->read('4muc5gl98q850vt...')
#2 /data/web/abcd/html/verlag_2.19/vendor/magento/framework/Session/SaveHandler.php(93): Magento\Framework\Session\SaveHandler\Native->read('4muc5gl98q850vt...')
#3 [internal function]: Magento\Framework\Session\SaveHandler->read('4muc5gl98q850vt...')
#4 /data/web/abcd/html/verlag_2.19/vendor/magento/framework/Session/SessionManager.php(189): session_start()
#5 /data/web/abcd/html/verlag_2.19/var/generation/Magento/Backend/Model/Auth/Session/Interceptor.php(167): Magento\Framework\Session\SessionManager->start()
#6 /data/web/abcd/html/verlag_2.19/vendor/magento/framework/Session/SessionManager.php(130): Magento\Backend\Model\Auth\Session\Interceptor->start()
#7 /data/web/abcd/html/verlag_2.19/vendor/magento/module-backend/Model/Auth/Session.php(98): Magento\Framework\Session\SessionManager->__construct(Object(Magento\Framework\App\Request\Http), Object(Magento\Framework\Session\SidResolver\Proxy), Object(Magento\Framework\Session\Config), Object(Magento\Framework\Session\SaveHandler), Object(Magento\Framework\Session\Validator), Object(Magento\Framework\Session\Storage), Object(Magento\Framework\Stdlib\Cookie\PhpCookieManager), Object(Magento\Framework\Stdlib\Cookie\CookieMetadataFactory), Object(Magento\Framework\App\State))
#8 /data/web/abcd/html/verlag_2.19/var/generation/Magento/Backend/Model/Auth/Session/Interceptor.php(14): Magento\Backend\Model\Auth\Session->__construct(Object(Magento\Framework\App\Request\Http), Object(Magento\Framework\Session\SidResolver\Proxy), Object(Magento\Framework\Session\Config), Object(Magento\Framework\Session\SaveHandler), Object(Magento\Framework\Session\Validator), Object(Magento\Framework\Session\Storage), Object(Magento\Framework\Stdlib\Cookie\PhpCookieManager), Object(Magento\Framework\Stdlib\Cookie\CookieMetadataFactory), Object(Magento\Framework\App\State), Object(Magento\Framework\Acl\Builder\Proxy), Object(Magento\Backend\Model\Url), Object(Magento\Backend\App\Config))

In the configuration options I have tried both Session and Db, but the outcome is the same...

Answer 1

Unless you have redis installed and configured correctly this will happen.

If you open your app/etc/env.php file you will see a couple of nodes in there which relate to redis cache. You can just remove these. Should look something like this :

'cache' =>
array(
   'frontend' =>
   array(
      'default' =>
      array(
         'backend' => 'Cm_Cache_Backend_Redis',
         'backend_options' =>
         array(
            'server' => '127.0.0.1',
            'database' => '0',
            'port' => '6379'
            ),
    ),
    'page_cache' =>
    array(
      'backend' => 'Cm_Cache_Backend_Redis',
      'backend_options' =>
       array(
         'server' => '127.0.0.1',
         'port' => '6379',
         'database' => '1',
         'compress_data' => '0'
       )
    )
  )
),

You can just get rid of the whole thing.

Sessions are similar in this regard. In env.php you may see a section like this :

'session' =>
array (
  'save' => 'redis',
  'redis' =>
  array (
    'host' => '127.0.0.1',
    'port' => '6379',
    'password' => '',
    'timeout' => '2.5',
    'persistent_identifier' => '',
    'database' => '2',
    'compression_threshold' => '2048',
    'compression_library' => 'gzip',
    'log_level' => '1',
    'max_concurrency' => '6',
    'break_after_frontend' => '5',
    'break_after_adminhtml' => '30',
    'first_lifetime' => '600',
    'bot_first_lifetime' => '60',
    'bot_lifetime' => '7200',
    'disable_locking' => '0',
    'min_lifetime' => '60',
    'max_lifetime' => '2592000'
  )
),

Just change it to :

'session' => 
  array (
    'save' => 'db', // or 'files'
  ),