rss feed stopped working

[spiros]

For this:
http://www.translatum.gr/forum/index.php
http://www.translatum.gr/forum/index.php?type=rss;action=.xml


This feed does not validate.
line 1, column 0: XML parsing error: <unknown>:1:0: no element found
https://validator.w3.org/feed/check.cgi?url=http%3A%2F%2Fwww.translatum.gr%2Fforum%2Findex.php%3Ftype%3Drss%3Baction%3D.xml