You are using v1.2 (two) of Leviathan and the curren tversion compatible with PHP 7.x is V1.12 (twelve). So you need to backup and update the template to the latest version. You will need a suitable subscription to be able to do this.
Also, Gantry 4 latest version is v4.1.37 so you need to update that too.
Finally ensure that all RT extensions are also brought up to latest versions too.
Regards, Mark.
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