Error Importing from Joomla3

I’m trying to Import from my Joomla3 installation following this instructions:

Unfortunately I receive an error which I don’t understand. Thanks in advance for help!

`ubygems.rb' is deprecated, and will be removed on or after 2018-12-01. Remove `-rubygems' from your command-line, or use `-r rubygems' instead
Traceback (most recent call last):
	2: from -e:2:in `<main>'
	1: from /home/eyetec/.gem/ruby/2.5.0/gems/jekyll-import-0.15.0/lib/jekyll-import/importer.rb:25:in `run'
/home/eyetec/.gem/ruby/2.5.0/gems/jekyll-import-0.15.0/lib/jekyll-import/importers/joomla3.rb:48:in `process': can't modify frozen String (FrozenError)

This is a known bug in the plugin and is being patched…

I suggest that you temporarily uninstall the 0.15.0 version and try again with an older version.
Apologies for the inconvenience.

Downgraded to 0.14 and Success! Thanks!