Originally Posted by Raze

It should already be fixed. Please email supportdos2@larian.com with the save that crashes when trying to overwrite it (or a Dropbox or Google drive link, etc).
Each save is a folder in the '..\Documents\Larian Studios\Divinity Original Sin 2\PlayerProfiles\<ProfileName>\Savegames\Story' folder.
In Windows Explorer you can zip file(s) and folder(s) by right clicking on it/them and selecting 'Send To | Compressed (zipped) Folder'.

If this is the same issue, it is possible to check the save folders, and see if there are extra files in them, and separate/delete as required. The saves should just be a png screenshot file and lsv save file, having the same name as the save folders; any other files (globals.lsf or a levelcache folder conataining lsf files) are intended to be temporary, and should have been removed once the compressed lsv file was created.

Sending them will be difficult. What seems to be happening is that when I try to save, the save folder is created in the Temp folder and the .png file appears there, but the .lsv file never does. Doesn't seem to make a difference if I am quicksaving or trying to save a "named" file.