An XML validation error occurred and the XML could not be exported

Software Support
1

When I try to download XML file for crossref (DOI) using Crossref XML Export Plugin: I am not able to download Metadata is show error “An XML validation error occurred and the XML could not be exported.”

Doi error
Doi error1157×494 37 KB

And also I deposited article from OJS 3.4.0.3 site but not work DOI : https://doi.org/10.53037/na.v8i1.84

image
image1046×153 12.2 KB

Steps I took leading up to the issue
For example:

  1. Go to ‘CrossrefExportPlugin’
  2. Click on ‘Export DOI’
  3. See error ‘An XML validation error occurred and the XML could not be exported.’

I am using OJS 3.4.0.3

Please give me solution.