Index: t3lib/class.t3lib_flashmessagequeue.php
===================================================================
--- t3lib/class.t3lib_flashmessagequeue.php	(revision 9553)
+++ t3lib/class.t3lib_flashmessagequeue.php	(working copy)
@@ -55,11 +55,7 @@
 		if ($message->isSessionMessage()) {
 			$queuedFlashMessages = self::getFlashMessagesFromSession();
 			$queuedFlashMessages[] = $message;
-
-			$GLOBALS['BE_USER']->setAndSaveSessionData(
-				'core.template.flashMessages',
-				$queuedFlashMessages
-			);
+			self::storeFlashMessagesInSession($queuedFlashMessages);
 		} else {
 			self::$messages[] = $message;
 		}
@@ -77,10 +73,7 @@
 		$queuedFlashMessagesFromSession = self::getFlashMessagesFromSession();
 		if (!empty($queuedFlashMessagesFromSession)) {
 				// reset messages in user session
-			$GLOBALS['BE_USER']->setAndSaveSessionData(
-				'core.template.flashMessages',
-				null
-			);
+			self::removeAllFlashMessagesFromSession();
 		}
 
 		$queuedFlashMessages = array_merge($queuedFlashMessagesFromSession, self::$messages);
@@ -92,13 +85,46 @@
 	}
 
 	/**
+	 * Stores given flash messages in the session
+	 *
+	 * @param	array	array of t3lib_FlashMessage
+	 * @return	void
+	 */
+	protected static function storeFlashMessagesInSession(array $flashMessages) {
+		if (TYPO3_MODE === 'BE') {
+			$GLOBALS['BE_USER']->setAndSaveSessionData('core.template.flashMessages', $flashMessages);
+		} else {
+			$GLOBALS['TSFE']->fe_user->setKey('ses', 'core.template.flashMessages', $flashMessages);
+			$GLOBALS['TSFE']->fe_user->storeSessionData();
+		}
+	}
+
+	/**
+	 * Removes all flash messages from the session
+	 *
+	 * @return	void
+	 */
+	protected static function removeAllFlashMessagesFromSession() {
+		if (TYPO3_MODE === 'BE') {
+			$GLOBALS['BE_USER']->setAndSaveSessionData('core.template.flashMessages', NULL);
+		} else {
+			$GLOBALS['TSFE']->fe_user->setKey('ses', 'core.template.flashMessages', NULL);
+			$GLOBALS['TSFE']->fe_user->storeSessionData();
+		}
+	}
+
+	/**
 	 * Returns current flash messages from the session, making sure to always
 	 * return an array.
 	 *
 	 * @return	array	An array of t3lib_FlashMessage flash messages.
 	 */
 	protected static function getFlashMessagesFromSession() {
-		$flashMessages = $GLOBALS['BE_USER']->getSessionData('core.template.flashMessages');
+		if (TYPO3_MODE === 'BE') {
+			$flashMessages = $GLOBALS['BE_USER']->getSessionData('core.template.flashMessages');
+		} else {
+			$flashMessages = $GLOBALS['TSFE']->fe_user->getKey('ses', 'core.template.flashMessages');
+		}
 		return is_array($flashMessages) ? $flashMessages : array();
 	}