Hi,

To fix this issue, please go to file: app\design\frontend\default\sns_ostore\layout\checkout.xml find the text ‘checkout_onepage_success’ and replace the bellow code:
<action method=”setTemplate”><template>page/2columns-right.phtml</template></action>
By:
<action method=”setTemplate”><template>page/1column.phtml</template></action>

Similarly, you do this with the text ‘checkout_onepage_failure’ !

Thanks!