Sony has released Vita system update 3.18.
The company says the mandatory update "improves system stability during use of some features".
Reddit users speculate that the update was designed to fix an exploit that allowed users to run homebrew software via the PSP emulator.
Sony said in late July that combined Vita and PSP sales came in at 750,000 units during the company's first financial quarter. The figure was up from 600,000 during the same period a year earlier and 700,000 in the prior quarter.
Vita continues to perform well in Japan, where it's now supported by a growing range of locally made software.
However, sales in the west have been less encouraging, and the system's prospects outside of Japan are uncertain.
Sony Computer Entertainment CEO Andrew House said in July: "I certainly think you'll still see Vita as a triple-A machine in Japan where it has a different function with the console dynamic of the marketplace. That for me is a given.
"It's hard to say in terms of the other markets. I think remote play is still in its nascent stages, I think we need to have better understanding. We know a lot of players are embracing it and using it and seem to like the experience a lot, but necessarily that changes the dynamic."