Esri's geometry service fails to recognize Well-known ID 6783.
Last Published: December 22, 2016ArcGIS Online
Bug ID Number
December 16, 2015
March 30, 2022
After review by the development team, it has been determined that this issue is related to a known limitation with the software that lies outside of Esri's control. The issue's Additional Information section may contain further explanation.
Wkid 6783 was introduced in 10.3.1. The REST API document that is referenced, http://resources.arcgis.com/en/help/arcgis-rest-api/index.html#//02r300000105000000 is the document for the latest release, which is 10.3.1.
From inside the server, if the API Reference link in the upper right of the Project page is selected, it launches the document for the server release which is 10.3.
Visit the following page, https://utility.arcgisonline.com/arcgis/rest/services/Geometry/GeometryServer/project.
Click on the API Reference link in the upper right hand corner.
Since the server is 10.3, this launches the 10.3 document. Searching for 6783 on this page returns no result.
In summary, the API reference from REST is the document that is shipped with the server release. If a user has the most up to date release of the software, then they might want to check on resources.arcgis.com to see if there have been any updates. However, if they have an older version of the software, resources.arcgis.com may not apply. So the short answer is that the REST document is relevant to the user’s installed software, while resources.arcgis.com may not be.
Use Well-known ID 104223 in place of Well-known ID 6783. They both refer to GCS_NAD_1983_CORS96.