When i add a product to my cart, and click to go to my cart, it goes to a blank white page. I'm currently trying to get the USPS API to work correctly, In debug mode, the white page says
Debug: plgSystemCartRates::onAfterRender() 'attachto' not defined. Defaulting to after Checkout link.
so it happened when you enabled the usps?
Yes, i just updated it to V4.2, and enabled it.
i am moving this to the usps forum
Disable plgSystemCartRates until you've got the module working.