With the release of the new World Magnetic Model 2020, ArcGIS for Maritime: Server user will need to download a compatible WMM.COF file from https://www.ngdc.noaa.gov/geomag/WMM/wmm_ddownload.shtml.
The WMM.COF file is used to calculate the current compass rose values for magnetic variation (MAGVAR) point features when the compass rose display property is enabled. If the WWM.COF file is outdated, it will not load into the system and the values from the MAGVAR point feature are used.
Once downloaded, copy the WMM.COF file to your <ArcGIS Server Installation Directory>\MaritimeServer\Server<version>\maritimechartservice\controlfiles folder.
Next, you must copy the WMM.COF file to each of your Maritime Chart Service deployments and restart the associated map service.
All configuration files are under your controlFilesDirectory location, which is typically <Installation path>:\arcgisserver\directories\maritimeserver\maritimechartservice.
This location is in your controlFilesDirectory property of your map service; see Modifying Maritime Chart Service capabilities properties for additional information on setting this location.
For more information regarding this update, please email firstname.lastname@example.org.