After installing therion 6.3.3 (and Survex 1.4.15) on Windows 10 Pro, I get this error: "no usable coordinate transformation found" Full log here: https://pastebin.com/Dkn95nzE It seems that Therion uses the PROJ installation from my QGIS installation (QGIS updated the PROJ path and it points to proj.db file path from QGIS's PROJ package). After installing updated PROJ separately using << osgeo4w-setup.exe -q -k -r -A -s https://download.osgeo.org/osgeo4w/v2/ -P proj >> I get a similar error. This time it doesn't find the proj.db file at all: https://pastebin.com/TcEDbKmF It seems like Therion/PROJ library is using the path defined in the PROJ_LIB path variable so you need to set it back to the proj.db file version path that comes in the therion installation directory, in my case: SET PROJ_LIB="C:\Program Files\Therion\lib\proj-9\" You can set this globally or for the current batch session only if you don't want permanent path modification, in case QGIS or other software need it as it was before. If you want to see details on errors from PROJ library, you can set a debug flag SET PROJ_DEBUG=3 Is there another fix? Maybe a future fix would be for Therion to use it's PROJ distributable instead of the default one in the system, if possible. Alex -- This email has been checked for viruses by Avast antivirus software. www.avast.com