This happened upon pressing the 30-day increment button right after setting the secondary special order for each of my 6 geosurvey ships (each in its own task group) to "Refuel in current system. " Before this, the secondary special order was blank, and the primary special order was "Survey Next Five System Bodies" (and still is)
And this error message came up exactly 6 times, the same as my number of task groups which I updated with that order.
Immediately after this happened, I went back into the task group screen and selected one of my ships in the "Name" menu on the top right. Upon selecting it, this new error came up:
Title Bar: Error in PopulateMoves
Error 94 was generated by Aurora
Invalid use of Null
Please report to . . . etc.
followed immediately by:
Title Bar: Error in Populatemoves
Error 381 was generated by Aurora
Invalid property array index
Please report to . . . etc.
This exact thing happened to me, too, except I only had 2 geosurvey ships (in two task groups) and that they had the "refuel in current system" secondary order on from the start. The error didn't start occurring untill the first on ran out of system bodies to survey and started using the secondary order. Now, every time I select that task group in the task group screen, I get the same two errors, even though it no longer has any orders. Moving the ship out of the task group and then deleting it (the TG), resolves the issue.
Edit: I also get the 76 error, whenever I start the game. I didn't get that on the first game, but after deleting it and starting a new one, it shows up every time.
The advanced designs in for engines, weapons, etc. that were available for research on my first game, were apparantly deleted along with the game, because they didn't appear in the second game.