xmlrpc fails

Posting a message containing a link with a blog client using the “Direct Upload” xmlrpc mechanism (tried several, all fail in substantially identical way).

Most have two kinds of links: img and href. Both involve uploading file(s) from your computer to blog host. Images work fine. Some href’fed files work (e.g., .txt files, .html, even .exe) but others don’t work (e.g., .pdf files, .odt files).

The ones that don’t work generate error messages that seem to indicate some sort of a problem with xmlrpc, such as

An error occurred while uploading the post.
Error uploading images.
XML Parsing Error: Invalid procedure call or argument.