Hi Iam Jin-tae Kim, an South Korea ArcGIS User.
When I Printing a WebMap in ArcMap 10.6.1, I met an Error Message and Print Failed.
ERROR 000800: The value is not a member of MAP_ONLY
I found This Error Message on ArcGIS Server Manager Log.
Before I did this, I changed the Protocol on ArcGIS Server to HTTP Only -> HTTP & HTTPS, and I also added HTTPS for the web adapter.
Hey Jin-tae
I believe that there are no layout templates currently in your Layout templates directory. The following documentation would help with this.
It would also be good to test a print from a webmap to see if it encounters the same error.
Hope that helps,
David