After installing 17.1, I found that I am missing the submit button and also see other errors while navigating through the product.
The problem was that they had customized 14.1 and then tried to copy their custom files from 14.1 into %USM_HOME%\filestore\custom
in the 17.1 environment.
The 17.1 environment has been completely redesigned and you cannot take any files from 14.1 and copy them into 17.1
If you have customized files in 14.1 under %USM_HOME%\filestore\custom then you need to make the equivalent changes to the 17.1 files. You cannot use the older 14.1 files.