Nevertheless, the plugin maintains backward compatibility and it is able to load both files with the new (v1.2.0) and old formats (v1.1.3 and earlier).
There is only one exception: if you have XML files exported by v1.1.3 or earlier that contain workflows with the post-function to "Update Blocked Issues". This post-function is defined in a predefined script in Script Runner Plugin. In this case, the file will not load with version 1.2.0 of the plugin.
If you want to fix a file in this situation to have it loaded with new versions of the plugin, it is quite easy to do it:
Save the XML file and you are ready to go!