ArcGIS Enterprise 10.9.x, part of the ArcGIS 2021 releases, is the last release of ArcGIS Enterprise to support services published from ArcMap. Beginning with the ArcGIS 2022 releases, it will no longer be possible to publish new services from ArcMap and ArcMap-based ArcPy to ArcGIS Server sites. Esri highly recommends that all customers transition all publishing workflows to ArcGIS Pro at this time.
ArcGIS Enterprise 10.9.x will also be the last release series that supports running certain types of existing services originally published from ArcMap. Beginning with the ArcGIS 2022 releases, some ArcMap-based services will no longer be able to run if present during an upgrade. While many services that were originally published from ArcMap will continue to run on future releases, some specific service types must be re-authored and re-published. This includes geoprocessing services and ArcMap-based services that make use of SOEs or SOIs.
To prepare for this change, Esri recommends that customers consider republishing existing services using ArcGIS Pro. Review the following ArcGIS blog for information on data sources and types of services that must be re-published.