I am getting the same error.  I've prepared a Virginia resident return and need to attach a pdf copy of a New Mexico nonresident return in order to e-file Virginia.  The attach pdf works fine but I get the critical diagnostic that VA does not allow special characters in the file description so I think it's complaining about the period in the .pdf file extension.  I take the .pdf off the description and still get the error.  I also need to attach a pdf of Form- 41359 Pass-Through Withholding to the New Mexico return and that's not working either.  This needs to be fixed quickly by Intuit.