If you have recently upgraded Magento, and you have a custom template, you will notice that you are unable to login as a customer into the site. There is a simply fix for this. Two files must be changed. I have been fixing numerous sites recently, so I thought I’d share.
and paste this right after the code above:
<input type=”hidden” name=”form_key” value=”<? echo Mage::getSingleton(‘core/session’)->getFormKey(); ?>” />
2. app/design/frontend/(themepackage(/(theme)/template/persistent/customer/form/login.phtml and apply the same changes.
3. Clear your cache in Magento.
This should fix the login issue where people are unable to login in Magento after upgrading from 1.4, 1.5, 1.6, 1.7, etc. to Magento 1.8 or 1.8.1.