sf-retrieve-metadata-unpackaged-kwarg-not-package-xml-string
SfdcMetadataApi.retrieve() does not accept a package_xml string as a positional arg. The correct call uses the unpackaged kwarg with a dict of metadata types to members: conn.mdapi.retrieve(unpackaged={‘ApexClass’: [’*’]}). Passing a package XML string as a positional arg is treated as a URL path segment causing 404 errors.