I get the exact same error for my 1.12 save game as well.
Oh dear. I was sure I fixed that
In the meantime, here is the fix:
Open up your save game in a text editor like notepad, or textpad.
Search for this (its near the top)
change it to be
Then save it. Should work fine. Sorry about that!
Wich program did you use to open/edit the .xml file?
This suffix may be linked to the internet explorer or something equal that does not allow to edit and save, So just a double-click on the .xml-file would be useless. In this case try a right-click at the file to get the context menu and continue with ‘Edit’ so the file should be opened with some kind of editor like Word, Writer, WordPad, Notepad or something comparable.