The horizontal component of the national spatial reference system of Slovenia is based on EUREF GPS campaigns at the passive GNSS-network of EUREF sites in the years 1994–1996. Both active GNSS networks (the SIGNAL and Zero-Order Combined Geodetic Networks) were established afterwards, which caused inconsistencies in coordinates based on GNSS surveys. Furthermore, the national coordinate reference system (D96) was supposed to expire after two decades from its realization due to relatively active tectonics. A new GNSS campaign was carried out in 2016 in order to validate and improve the quality of coordinates of GNSS sites in Slovenia. The result is a new realization of ETRS89 referred to as D17. However, it was not implemented directly due to substantial coordinate differences when compared to the previous realization. A pragmatic approach was chosen that attempted to keep changes of coordinates as much small as possible. It eliminated inconsistencies but also distortions in GNSS networks caused by the changes in physical space. The new coordinates are based on both the old (D96) and new (D17) realizations of ETRS89 and are denoted by D96-17. According to the requirements for the quality of coordinates in the land cadastre surveys, all the previously determined coordinates of cadastral points remain unchanged. The main benefit of the update of coordinates in the core GNSS networks in the country is more precise and accurate positioning in the future.