UPDATE - Bethesda has just rolled out the patch. Check out the full details and fixes here.
Long game hours is a Bethesda trademark. It wouldn’t be surprising if you spend hundreds of hours in a single playthrough in Starfield. However, there seems to be a bug that prevents you from enjoying that by simply crashing your game unless you jump into the Unity again for NG+.
According to modder Nukem, the issue results from the game reaching its limit in Form IDs, which is at 4,000,000 or the hexadecimal 0xff3f0000 range. When the game reaches that limit, it can no longer generate new form IDs and crashes.
Instead of fully cleaning up old form IDs that are no longer used, Nukem said that Starfield continues generating form IDs at the last range at which it did so. With the size of the game and the number of objects that need to be generated, the game inevitably reaches that limit at a certain number of hours, depending on how active the player is.
Regrettably, the only way to avoid hitting that limit is to travel to another universe and initiate NG+, which then refreshes all the form IDs.
On the other hand, user SpareDifficult posted that same issue in the Starfield subreddit and got a reply from a Bethesda community manager. The manager said there will be an update this week to fix this issue and that they’ve been aware of the problem, which they said is “a high priority.”
Curiously, the Bethesda manager said that the crash was due to a memory leak and not by form ID generated, as explained by Nukem.
Did you know that there are hidden dev rooms in Starfield? Find out where they are using this guide.