Problem: File name is modified when signing an add-in with the ESRISignAddIn utility
When digitally signing an add-in file with the ESRISignAddIn utility, the file name of an .xml file included in the add-in is modified if it contains spaces. The spaces are replaced with '%20'.
When an .xml file name contains a space, for example, ArcGIS Options.xml, the space in the file name is replaced with %20 to become ArcGIS%20Options.xml, which is a URL-encoded format for a blank space. As a result, the .xml files compiled in an add-in placed in a generated subfolder can no longer be found as the file name has been changed.
Solution or Workaround
Rename the .xml files and avoid using spaces.