I found the following thread about ns_xml.
https://openacs.org/forums/message-view?message_id=19169However, I still see no need for ns_xml.
In my view tdom is its substitute? Isn't it? I installed TDOM package 0.8, then restarted Naviserver, but ns_xml errors remains.
tdom 0.8.3~20080525-3+nmu2 A fast XML/DOM/XPath/XSLT extension for Tcl written in C
AOLSERVER 4.5 was previously uninstalled from this server. I ran apt-get remove --purge aolserver-* , then NaviServer took place. The installation was successful.
Would aolserver's removal be a potential cause?