I am afraid I can't disable all the plugins. This is a Multisite installation and many plugins are Network Activated rather then Local. Is there no other way ?
The Free Duplicator will not duplicate single site on a multisite. Is there another way you can debug this ? I can provide you with a list of active plugins that this particular site is using.
We purchased the Multisite Extension for the All-in-one plugin since it looks like it's something we need anyways. I will be installing it tomorrow AM, and will provide you with the subsite backup.
[Fri Jun 01 11:50:17 2018] [error] [client 108.41.142.17] PHP Fatal error: Can't inherit abstract function ICRED_Field_Command::execute() (previously declared abstract in CRED_Field_Command_Base) in /var/www/html/wordpress-multisite/wp-content/plugins/cred-frontend-editor/application/models/field/command/base.php on line 6, referer: hidden link