Hello again :)
I took a quick look at the code that displays this error, it is a prevention of save data getting corrupt.
I found one bug that could be related to it and hotfixed it, the update is live, just reload your game. I hope this fixes that problem, it could appear more on lower spec pc's, especially with lesser CPU/Network capabilities.
If it keeps happening please send a screenshot of the F12 console, there should be something related to saving or loading data.
Glad you enjoy the game!