Hi,
 
I have a magento version 1.5.0. I need to upgrade the magento to 1.9.3 version. I am a web developer. But not an expert in magento.  My site is hosted on http://nublue.co.uk. I have read many documentation for the upgrade. Finally decided to upgrade from the magento connect.  I have copied my site in to a sub folder (dev) and tried to upgrade magento there. At the magento connect, i have upgraded using the 'connect20.magentocommerce.com/community/Mage_All_Latest ' key and done the upgrade process. But  on the end of condole content it shows as the
 
"
Cleaning cache
.........................................................................................................................................................................................................................................................................................................................................................................
Exception during cache and session cleaning
 
"
 
Also checked the var /report file and it shows the following:
 
SQLSTATE[42000]: Syntax error or access violation: 1091 Can't DROP 'IDX_SORT_ADDED_AT'; check that column/key exist
 
 
Can some one assist me. I need to upgrade this asap. Any help would be great appreciateble.
 
Thanks in advance.