I upgraded from Magento CE 1.8.1 to 1.9.0.1 and now the FedEx and USPS shipping modules I had set up do NOT work, as in they do not show in the shipping step at checkout.
At first I thought it might be a Theme / Template issue since I am finding that virtually ALL of the Themes that I have tried, that worked fine with 1.8.1 have problems somewhere with 1.9.0.1 so I set it to the RWD Default theme that was part of the 1.9.0.1 Magento CE install, but it did not fix the shipping problems.
I was using the following in 1.8.1 with no problems:
Free Shipping
FedEx
USPS
UPS
Now the only two I can get to work are UPS and Free Shipping. The UPS module is really not that great as it does not factor return accurate shipping values.
Any help would be appreciated. ( I have cleared the cache and have tried enabling / disabling the shipping options to no avail.)
Best Answer
As of September the USPS API system has changed. This basically requires a few patches for Magento. Full information on the changes can be found at the following links.
I suggest that you will have to download the patch from Magento and test that these shipping methods are now working.