I can load your save in the public and developer build of the previous version of the game. In the latest release (public and developer), it crashes at the very end of the loading process.
I will create a bug report to get a programmer to take a look at this.
To revert to the previous game version:
With the GOG release, in Galaxy select the game, click More and select Settings, then uncheck automatic updates, in order to manually select the last update.
With Steam, it is possible to download previous versions of games using a console in the client. See
this guide and the
related screenshots.
Note that the guide suggests moving the current install folder and replacing it with the downloaded version, but it would be easier to leave the current install in place, and move the downloaded folder wherever you want to play from (perhaps renaming it 'DOS2 old version', or something), and start it from the executable.
After confirming the previous version works, you can delete the 'bin', 'Classic' and 'Data' folders from its main folder, since you don't need a duplicate of the original release of the game (just the 'DefEd' folder).