Index: t3lib/class.t3lib_db.php
===================================================================
--- t3lib/class.t3lib_db.php	(revision 7449)
+++ t3lib/class.t3lib_db.php	(working copy)
@@ -1081,10 +1081,8 @@
 
 			// check if MySQL extension is loaded
 		if (!extension_loaded('mysql')) {
-			$header = 'Database Error';
-			$message = 'It seems that MySQL support for PHP is not installed!';
-			t3lib_timeTrack::debug_typo3PrintError($header, $message, false, t3lib_div::getIndpEnv('TYPO3_SITE_URL'));
-			exit;
+			$message = 'Database Error: It seems that MySQL support for PHP is not installed!';
+			throw new RuntimeException($message, 1271492606);
 		}
 
 			// Check for client compression
Index: typo3/sysext/cms/tslib/class.tslib_fe.php
===================================================================
--- typo3/sysext/cms/tslib/class.tslib_fe.php	(revision 7449)
+++ typo3/sysext/cms/tslib/class.tslib_fe.php	(working copy)
@@ -487,7 +487,16 @@
 	 * @return	void
 	 */
 	function connectToDB()	{
-		if ($GLOBALS['TYPO3_DB']->sql_pconnect(TYPO3_db_host, TYPO3_db_username, TYPO3_db_password))	{
+		try {
+			$link = $GLOBALS['TYPO3_DB']->sql_pconnect(TYPO3_db_host, TYPO3_db_username, TYPO3_db_password);
+		} catch (RuntimeException $e) {
+			if (TYPO3_db) {
+					// Database is defined, this should normally not happen, user should be informed
+				throw $e;
+			}
+			$link = FALSE;
+		}
+		if ($link !== FALSE) {
 			if (!TYPO3_db)	{
 				$this->printError('No database selected','Database Error');
 					// Redirects to the Install Tool: