Resolved with modifications.
Unable to checkout, alert Error Message pops up during final checkout "There was an error processing your order.Please contact us or try again later"
To solve, follow these instructions:
1. Copy "app/code/community/TBT/RewardsModel/Sales/Order.php" and "app/code/community/TBT/RewardsModel/Sales/Quote.php" to app/code/local/TBT/Rewards/Model/Sales/Order.php and "app/code/local/TBT/RewardsModel/Sales/Order.php" so that you are not modifying core extension files.
2. Replace Mage_Sales_Model_Order with Upgradecvv_Paymentwipe_Model_Order in (Order.php) .
Replace Mage_Sales_Model_Quote with Upgradecvv_Paymentwipe_Model_Quote in (Quote.php) .
3. Open app/etc/modules/TBT_Rewards.xml and locate the following in lines 7-13:
<depends> <TBT_Common/> <Mage_Rule/> <Mage_Catalog/> <Mage_Sales/> <Mage_Customer/> </depends>
4. Add the following dependency to the node (see Resolving extension conflicts):
5. Upload new and modified files to your server.
6. Clear your cache.
Please keep in mind that implementing any modifications to your MageRewards core code does void your support agreement because you're adding dependency to the other module.