Please make sure that you have installed all updates available at Installer - Updates.
Make sure that you have installed updates of your design theme at Shop - Storefront. If an update is available there will be a link "Update to version ... is available" displayed. We strongly recommend you to install the update if it is available. But you have to be careful because when you install the update all modifications made in design theme templates will be lost and theme will be reverted to it's original state. A good practice is to make a backup of your design theme before installing the updates. To make a backup you may click the "Clone theme" link and also you may click "Download theme backup" link to get a copy of theme files into your PC's hard disk drive.
After installing the updates please clear the cache at Installer - Settings : Clear cache.