Fail to locate main schema resource

Can’t locate/access schema from URL? Note that schema can be accessed from browser.

Command: xmllint --schema mpd-catalog.xml

error : Unknown IO error
warning: failed to load external entity “
Schemas parser error : Failed to locate the main schema resource at ‘

Please review the command invocation. I get the same error message when I try it. My guess is that xmllint does not handle xml files over HTTP, so you’ll need to fetch the schema separately and specify it as a local file.