Unchecking DNS on the MTA tab results in

zimbra JavaScript error encountered in method ZaXFormViewController.prototype.runValidationStack

message: E[C] has no properties fileName: lineNumber: 6153 stack: (undefined)@ call([object Object],undefined)@:0 (undefined)@

I have done
zmcontrol stop
rm -rf /opt/zimbra/jetty/work/*
cleared browser cache
and retried but I received the same error.

I have a work around in place but what does this error mean?