This happens to me almost every time I try to load an old game. Searching the forum shows posts related to this bug going back to 2017. When will this bug be a high enough priority to fix?
Thanks!
The (current) reasons for that error are not known, some previous instances could be identified to belong to Smugglers, for example.
If you are trying to reload very old games that might happen more often, but for recent games I come across that only sometimes.