Error message

PDOException: SQLSTATE[HY000] [1040] Too many connections in db_select() (line 2640 of /data/www/drupal/includes/database/database.inc).

Error

The website encountered an unexpected error. Please try again later.

( ! ) Fatal error: Uncaught PDOException: SQLSTATE[08004] [1040] Too many connections in /data/www/drupal/includes/database/database.inc on line 335
Call Stack
#TimeMemoryFunctionLocation
10.18234358576_drupal_exception_handler( $exception = class PDOException { protected $message = 'SQLSTATE[HY000] [1040] Too many connections'; private ${Exception}string = ''; protected $code = 1040; protected $file = '/data/www/drupal/includes/database/database.inc'; protected $line = 335; private ${Exception}trace = [0 => [...], 1 => [...], 2 => [...], 3 => [...], 4 => [...], 5 => [...], 6 => [...], 7 => [...], 8 => [...], 9 => [...], 10 => [...], 11 => [...], 12 => [...], 13 => [...], 14 => [...], 15 => [...]]; private ${Exception}previous = NULL; public $errorInfo = [0 => 'HY000', 1 => 1040, 2 => 'Too many connections']; public $xdebug_message = '<tr><th align=\'left\' bgcolor=\'#f57900\' colspan="5"><span style=\'background-color: #cc0000; color: #fce94f; font-size: x-large;\'>( ! )</span> PDOException: SQLSTATE[HY000] [1040] Too many connections in /data/www/drupal/includes/database/database.inc on line <i>335</i></th></tr>\n<tr><th align=\'left\' bgcolor=\'#e9b96e\' colspan=\'5\'>Call Stack</th></tr>\n<tr><th align=\'center\' bgcolor=\'#eeeeec\'>#</th><th align=\'left\' bgcolor=\'#eeeeec\'>Time</th><th align=\'left\' bgcolor=\'#eeeeec\'>Memory</t' } ).../bootstrap.inc:0
20.18234359152_drupal_log_error( $error = ['%type' => 'PDOException', '!message' => 'SQLSTATE[HY000] [1040] Too many connections', '%function' => 'db_select()', '%file' => '/data/www/drupal/includes/database/database.inc', '%line' => 2640, 'severity_level' => 3], $fatal = TRUE ).../bootstrap.inc:2670
( ! ) PDOException: SQLSTATE[08004] [1040] Too many connections in /data/www/drupal/includes/database/database.inc on line 335
Call Stack
#TimeMemoryFunctionLocation
10.18234358576_drupal_exception_handler( $exception = class PDOException { protected $message = 'SQLSTATE[HY000] [1040] Too many connections'; private ${Exception}string = ''; protected $code = 1040; protected $file = '/data/www/drupal/includes/database/database.inc'; protected $line = 335; private ${Exception}trace = [0 => [...], 1 => [...], 2 => [...], 3 => [...], 4 => [...], 5 => [...], 6 => [...], 7 => [...], 8 => [...], 9 => [...], 10 => [...], 11 => [...], 12 => [...], 13 => [...], 14 => [...], 15 => [...]]; private ${Exception}previous = NULL; public $errorInfo = [0 => 'HY000', 1 => 1040, 2 => 'Too many connections']; public $xdebug_message = '<tr><th align=\'left\' bgcolor=\'#f57900\' colspan="5"><span style=\'background-color: #cc0000; color: #fce94f; font-size: x-large;\'>( ! )</span> PDOException: SQLSTATE[HY000] [1040] Too many connections in /data/www/drupal/includes/database/database.inc on line <i>335</i></th></tr>\n<tr><th align=\'left\' bgcolor=\'#e9b96e\' colspan=\'5\'>Call Stack</th></tr>\n<tr><th align=\'center\' bgcolor=\'#eeeeec\'>#</th><th align=\'left\' bgcolor=\'#eeeeec\'>Time</th><th align=\'left\' bgcolor=\'#eeeeec\'>Memory</t' } ).../bootstrap.inc:0
20.18234359152_drupal_log_error( $error = ['%type' => 'PDOException', '!message' => 'SQLSTATE[HY000] [1040] Too many connections', '%function' => 'db_select()', '%file' => '/data/www/drupal/includes/database/database.inc', '%line' => 2640, 'severity_level' => 3], $fatal = TRUE ).../bootstrap.inc:2670
30.19954402544ThemeRegistry->__destruct( ).../bootstrap.inc:0
40.19954402920ThemeRegistry->set( $data = ['table' => ['variables' => [...], 'type' => 'module', 'theme path' => 'modules/system', 'function' => 'theme_table']], $lock = ??? ).../bootstrap.inc:464
50.19954403000lock_acquire( $name = 'theme_registry:runtime:dabar_theme:cache', $timeout = ??? ).../theme.inc:449
60.19984416816lock_may_be_available( $name = 'theme_registry:runtime:dabar_theme:cache' ).../lock.inc:146
70.19984417192db_query( $query = 'SELECT expire, value FROM {semaphore} WHERE name = :name', $args = [':name' => 'theme_registry:runtime:dabar_theme:cache'], $options = ??? ).../lock.inc:167
80.19984417568Database::getConnection( $target = 'default', $key = ??? ).../database.inc:2467
90.19984417568Database::openConnection( $key = 'dabar', $target = 'default' ).../database.inc:1582
100.19984418008DatabaseConnection_mysql->__construct( $connection_options = ['database' => 'dabar', 'username' => 'normatives_r', 'password' => 'sdf9023AD_t4', 'host' => 'localhost', 'driver' => 'mysql'] ).../database.inc:1796
110.19984418856DatabaseConnection_mysql->__construct( $dsn = 'mysql:host=localhost;port=3306;charset=utf8;dbname=dabar', $username = 'normatives_r', $password = 'sdf9023AD_t4', $driver_options = [1000 => TRUE, 20 => TRUE, 17 => TRUE, 1013 => FALSE] ).../database.inc:347
120.19984420656__construct( $dsn = 'mysql:host=localhost;port=3306;charset=utf8;dbname=dabar', $username = 'normatives_r', $passwd = 'sdf9023AD_t4', $options = [1000 => TRUE, 20 => TRUE, 17 => TRUE, 1013 => FALSE, 3 => 2] ).../database.inc:335