If DominoPDF logging shows that your attachment / file conversion is failing with the error;
OpenOffice Conversion Failure.
OpenOfficeError: com.sun.star.lang.IllegalArgumentException: URL seems to be an unsupported one
The error that was returned by OpenOffice typically means the specified file cannot be found.
Instead of passing the input file as simply “myfile.xls” the solution is to fully qualify the path, for example, “c:\temp\attach\myfile.xls” and in this manner OpenOffice will successfully find the file.