diff --git a/phpBB/includes/db/mssql_odbc.php b/phpBB/includes/db/mssql_odbc.php
index 2ecc42cadf..dabdbd1a44 100644
--- a/phpBB/includes/db/mssql_odbc.php
+++ b/phpBB/includes/db/mssql_odbc.php
@@ -32,6 +32,7 @@ include_once($phpbb_root_path . 'includes/db/dbal.' . $phpEx);
 class dbal_mssql_odbc extends dbal
 {
 	var $last_query_text = '';
+	var $connect_error = '';
 
 	/**
 	* Connect to server
@@ -68,7 +69,24 @@ class dbal_mssql_odbc extends dbal
 			@ini_set('odbc.defaultlrl', $max_size);
 		}
 
-		$this->db_connect_id = ($this->persistency) ? @odbc_pconnect($this->server, $this->user, $sqlpassword) : @odbc_connect($this->server, $this->user, $sqlpassword);
+		if ($this->persistency)
+		{
+			if (!function_exists('odbc_pconnect'))
+			{
+				$this->connect_error = 'odbc_pconnect function does not exist, is odbc extension installed?';
+				return $this->sql_error('');
+			}
+			$this->db_connect_id = @odbc_pconnect($this->server, $this->user, $sqlpassword);
+		}
+		else
+		{
+			if (!function_exists('odbc_connect'))
+			{
+				$this->connect_error = 'odbc_connect function does not exist, is odbc extension installed?';
+				return $this->sql_error('');
+			}
+			$this->db_connect_id = @odbc_connect($this->server, $this->user, $sqlpassword);
+		}
 
 		return ($this->db_connect_id) ? $this->db_connect_id : $this->sql_error('');
 	}
diff --git a/phpBB/includes/db/mysql.php b/phpBB/includes/db/mysql.php
index 1ccb785150..ae36fe6425 100644
--- a/phpBB/includes/db/mysql.php
+++ b/phpBB/includes/db/mysql.php
@@ -30,6 +30,7 @@ include_once($phpbb_root_path . 'includes/db/dbal.' . $phpEx);
 class dbal_mysql extends dbal
 {
 	var $multi_insert = true;
+	var $connect_error = '';
 
 	/**
 	* Connect to server
@@ -44,7 +45,24 @@ class dbal_mysql extends dbal
 
 		$this->sql_layer = 'mysql4';
 
-		$this->db_connect_id = ($this->persistency) ? @mysql_pconnect($this->server, $this->user, $sqlpassword) : @mysql_connect($this->server, $this->user, $sqlpassword, $new_link);
+		if ($this->persistency)
+		{
+			if (!function_exists('mysql_pconnect'))
+			{
+				$this->connect_error = 'mysql_pconnect function does not exist, is mysql extension installed?';
+				return $this->sql_error('');
+			}
+			$this->db_connect_id = @mysql_pconnect($this->server, $this->user, $sqlpassword);
+		}
+		else
+		{
+			if (!function_exists('mysql_connect'))
+			{
+				$this->connect_error = 'mysql_connect function does not exist, is mysql extension installed?';
+				return $this->sql_error('');
+			}
+			$this->db_connect_id = @mysql_connect($this->server, $this->user, $sqlpassword, $new_link);
+		}
 
 		if ($this->db_connect_id && $this->dbname != '')
 		{
diff --git a/phpBB/includes/db/mysqli.php b/phpBB/includes/db/mysqli.php
index a311b8cda6..98b659723f 100644
--- a/phpBB/includes/db/mysqli.php
+++ b/phpBB/includes/db/mysqli.php
@@ -27,12 +27,19 @@ include_once($phpbb_root_path . 'includes/db/dbal.' . $phpEx);
 class dbal_mysqli extends dbal
 {
 	var $multi_insert = true;
+	var $connect_error = '';
 
 	/**
 	* Connect to server
 	*/
 	function sql_connect($sqlserver, $sqluser, $sqlpassword, $database, $port = false, $persistency = false , $new_link = false)
 	{
+		if (!function_exists('mysqli_connect'))
+		{
+			$this->connect_error = 'mysqli_connect function does not exist, is mysqli extension installed?';
+			return $this->sql_error('');
+		}
+
 		// Mysqli extension supports persistent connection since PHP 5.3.0
 		$this->persistency = (version_compare(PHP_VERSION, '5.3.0', '>=')) ? $persistency : false;
 		$this->user = $sqluser;
diff --git a/phpBB/includes/db/oracle.php b/phpBB/includes/db/oracle.php
index 62b36aa8bf..42f5de1b24 100644
--- a/phpBB/includes/db/oracle.php
+++ b/phpBB/includes/db/oracle.php
@@ -25,6 +25,7 @@ include_once($phpbb_root_path . 'includes/db/dbal.' . $phpEx);
 class dbal_oracle extends dbal
 {
 	var $last_query_text = '';
+	var $connect_error = '';
 
 	/**
 	* Connect to server
@@ -48,7 +49,33 @@ class dbal_oracle extends dbal
 			$connect = $sqlserver . (($port) ? ':' . $port : '') . '/' . $database;
 		}
 
-		$this->db_connect_id = ($new_link) ? @ocinlogon($this->user, $sqlpassword, $connect, 'UTF8') : (($this->persistency) ? @ociplogon($this->user, $sqlpassword, $connect, 'UTF8') : @ocilogon($this->user, $sqlpassword, $connect, 'UTF8'));
+		if ($new_link)
+		{
+			if (!function_exists('ocinlogon'))
+			{
+				$this->connect_error = 'ocinlogon function does not exist, is oci extension installed?';
+				return $this->sql_error('');
+			}
+			$this->db_connect_id = @ocinlogon($this->user, $sqlpassword, $connect, 'UTF8');
+		}
+		else if ($this->persistency)
+		{
+			if (!function_exists('ociplogon'))
+			{
+				$this->connect_error = 'ociplogon function does not exist, is oci extension installed?';
+				return $this->sql_error('');
+			}
+			$this->db_connect_id = @ociplogon($this->user, $sqlpassword, $connect, 'UTF8');
+		}
+		else
+		{
+			if (!function_exists('ocilogon'))
+			{
+				$this->connect_error = 'ocilogon function does not exist, is oci extension installed?';
+				return $this->sql_error('');
+			}
+			$this->db_connect_id = @ocilogon($this->user, $sqlpassword, $connect, 'UTF8'));
+		}
 
 		return ($this->db_connect_id) ? $this->db_connect_id : $this->sql_error('');
 	}
diff --git a/phpBB/includes/db/sqlite.php b/phpBB/includes/db/sqlite.php
index 8de72fd394..be0ad4fc8f 100644
--- a/phpBB/includes/db/sqlite.php
+++ b/phpBB/includes/db/sqlite.php
@@ -25,6 +25,8 @@ include_once($phpbb_root_path . 'includes/db/dbal.' . $phpEx);
 */
 class dbal_sqlite extends dbal
 {
+	var $connect_error = '';
+
 	/**
 	* Connect to server
 	*/
@@ -36,7 +38,24 @@ class dbal_sqlite extends dbal
 		$this->dbname = $database;
 
 		$error = '';
-		$this->db_connect_id = ($this->persistency) ? @sqlite_popen($this->server, 0666, $error) : @sqlite_open($this->server, 0666, $error);
+		if ($this->persistency)
+		{
+			if (!function_exists('sqlite_popen'))
+			{
+				$this->connect_error = 'sqlite_popen function does not exist, is sqlite extension installed?';
+				return $this->sql_error('');
+			}
+			$this->db_connect_id = @sqlite_popen($this->server, 0666, $error);
+		}
+		else
+		{
+			if (!function_exists('sqlite_open'))
+			{
+				$this->connect_error = 'sqlite_open function does not exist, is sqlite extension installed?';
+				return $this->sql_error('');
+			}
+			$this->db_connect_id = @sqlite_open($this->server, 0666, $error);
+		}
 
 		if ($this->db_connect_id)
 		{