Occurrence
After upgrading the MapInfo Professional version, all custom MapInfo Professional projections have be deleted.
Solution
If you have installed with the Discover Bundle, it includes a backup of the PRJ file, before the MapInfo Pro installer deletes it.
At the conclusion of the updating process a copy of the previous MapInfo Projection file is now placed in the User's Temp folder or in more recent versions, the Encom folder -
C:\Users\USERNAME\AppData\Roaming\Encom\Common\Projections\MapInfow_backup.prj
Or
C:\Users\USERNAME\AppData\Local\Temp\Mapinfow_old.prj
Starting from Discover 2017 Upodate (19.1.21264) Discover will automatically copy the Mapinfow.prj to the Encom.prj on startup, to keep any custom projections added to MapInfo's reprojection engine and the Discover reprojection engine.
Note:
It is best practice to not simply copy and paste the entire contents of the saved projection file over the top of the newly installed projection file, as any new projections added by MapInfo Professional, such as GDA 2020, will be deleted.
Instead, open the file in Notepad. Locate your custom projection lines (usually at bottom or top) within the 'MapInfow_backup.prj', and copy these manually into the new MapInfow.prj file located in your MapInfo Professional Program directory.
