What am I missing here?: The first link works on a server with 10.3.1 on it and returns an image - it is a raster dataset in ArcSDE. The second link is 10.6 on a different server that is in production, mosaic dataset and throws an error - <ServiceException code="InvalidLayers">
Parameter 'Layers' contains invalid values.
</ServiceException>
Everything in the URLs are the same as are the setting on the services the best I can tell. Ideas?
https://server/arcgis/services/AerialPhotography/2016AirPhotoLeafOff6Inch/ImageServer/WMSServer?FORMAT=image/jpeg&VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=0&STYLES=&SRS=EPSG:4326&WIDTH=256&HEIGHT=256&BBOX=-93.1256103515625,44.73502789951546,-93.1201171875,44.738929943073664
https://gisimg.co.dakota.mn.us/arcgis/services/AerialPhotography/2017AirPhotoLeafOff6Inch/ImageServer/WMSServer?FORMAT=image/jpeg&VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=0&STYLES=&SRS=EPSG:4326&WIDTH=256&HEIGHT=256&BBOX=-93.1256103515625,44.73502789951546,-93.1201171875,44.738929943073664
In your first link you have https://server
In the second on there is https://gisimg.co.dakota.mn.us
I entered both of these and both worked:
The first server is an internal server of an earlier version of Server and I am hiding the name in the example.
You tried the full URL I provided and didn't get an error, but got a 256 by 256 image returned to the browser?
If I put full the URL in Pro and Desktopn I get Error: Unspecified error. In ArcGIS Online it loads and goes to the area but is blank.
It looks like the section "Specifying Custom Parameters" is new in the latest documentation and not found in 10.3, perhaps a clue in the Notes section. http://desktop.arcgis.com/en/arcmap/latest/map/web-maps-and-services/using-wms-service-layers.htm