Microsoft is barring users from running game emulations on the Xbox Series X | S. On Thursday, Twitter user @gamr12, who’s involved with the distribution of the RetroArch emulation software on Xbox, posted the error message they received when attempting to launch emulated content.

“Unable to launch this game or app,” the message reads. “The game or app you’re trying to launch violates Microsoft Store policy and is not supported.” Other users with emulation software on the Xbox Series X | S report running into the same issue.

As pointed out by @gamr12, you can still emulate games on the Xbox Series X | S, but only if you put the device in Developer Mode, which you have to pay for. Microsoft seems to have only gotten rid of the option when the console’s put in Retail Mode, something all users can switch on for free with a little technical know-how.

While it’s still not clear what prompted the change, Alyanna, an active emulator fan who says she is a Microsoft Azure developer, claims she contacted an unnamed “friend at the Xbox QA team” about the issue weeks ago, who said the reason for the ban is Nintendo.

While the source and claims of the message haven’t been verified or confirmed, it reads, “The primary reason for the ban is related to legal issues with Nintendo.” “While emulating itself is not illegal, it can be used to play games from consoles that are still under copyright protection without permission, which can create issues with Nintendo and its affiliates.”

Microsoft’s rules technically don’t allow emulations, but the company typically looked the other way in the past, according to Kotaku. “We continually evolve our mechanisms for reviewing and taking enforcement actions on content distributed to the Store to ensure alignment with our Microsoft Store Policies,” Microsoft tells Kotaku. “Per 10.13.10, Products that emulate a game system or game platform are not allowed on any device family,” Microsoft says. The company didn’t immediately respond to The Verge’s request for comment.

If Nintendo is, indeed, the catalyst behind Microsoft’s decision, I won’t at all be surprised. Nintendo has long been a stickler for emulated games — unless, of course, the company itself can create and profit off of them (see: NES/SNES Mini, Nintendo Switch Online game packages, etc.). Nintendo, notably, sued the RomUniverse website for $1.2 million in 2019. Nintendo also went after Gary Bowser, a Canadian hacker selling Switch hacks, who has agreed to pay $10 million in fines and is currently serving a 40-month prison sentence.