I have the Exact same problem.
Ufile will not Save a PDF or Print to my printer.
It gives that stupid OOPS error with no proper error number or any other information as to why it wont work.
As seen in this image: http://imgur.com/kNePnSe
There is no support whatsoever for this issue in the Ufile help sections.
I have the latest updated version of Ufile 20.21, and the updater says that i have the latest version available.
I also have the latest released version of windows 10 Pro 64bit, Ver 1703, OS Build 15063
My solution to this problem was to use a different PC which had an older version of windows 10 Pro 64bit Ver 1607 OS Build 14393
It is very clear to me that the people at Ufile never bothered to test their product on the latest version of windows 10.
I am very angry with Ufile for the time i wasted with this issue today, and i feel as if they should financially compensate me for my wasted time in troubleshooting their buggy product.