You are probably trying to load a xml file that was prepared using earlier versions of the XBRL tool. This error is due to the change in XBRL Schema URL that MCA has brought in recently. You can follow the the steps i have shown in this video to resolve the error
https://www.youtube.com/watch?v=8EUCOedwoAM. I am going to copy paste the text based summary of the process shown in the video:
"1. The error is caused due to the change in the XBRL Schema URL. The previous URL was "
http://www.mca.gov.in/XBRL" and the current URL is "
https://www.mca.gov.in/V3XBRL". This url is present in the xbrl xml files.
2. To resolve this error, all you have to do is open the xbrl xml file in notepad and replace the old url with the new one. Effectively, you just have to insert "s" after "http" and "V3" before "XBRL" .
Once that is done, just save the xml file.
3. After saving, reload the xml file in the xbrl tool. Now it should load successfully and you should be able to validate as well as export the same to a pdf."