Hello Peter,
I've updateed the Joomla 3.6.4. Is it the problem?
Possible
Could you give us
full FTP and admin access
and our team will try to find solution special for You, FTP and admin access You can send to our contact form.
ordasoft.com/contact-us-form
Link on website
Detail description: How reproduce error
Site Admin
username
password
FTP
FTP host
FTP username
FTP password
Thanks,
Andrew
OrdaSoft team.