If it were my FedExv2 module, you'd definitely know it, haha.
The error points to missing functions in ps_product, which leads me to believe that either you've installed some modifications that were overwritten during the upgrade, or the modifications overwrote some of the new VM1.1.5 files.
Either way, your ps_product class file is missing some code. I'm not near my source to look at the VM115 code, so I can't tell you which it is.