Sony Bravia smart TV sets made in 2012 will no longer be able to show YouTube videos after 30 September.
The devices will not be capable of displaying videos from the site thanks to changes made by YouTube to the way it handles uploads.
As a result, the app for YouTube will be removed from Bravia TVs by the end of this month, Sony said.
Sony has released a list of the 50 models across the range of TV sets that will be affected by the change.
In a statement posted to its customer support site, Sony said the television sets were not losing access because of a "failure" of the set.
Instead, it said, recent changes made to YouTube "exceed the capability of the TV's hardware".
This is believed to refer to Google's recent decision to start encrypting all connections to its video-sharing site. Encrypting and decrypting data can be a computationally intensive task that the processors in Bravia sets that handle net-connected functions cannot cope with.
Some owners of affected TV sets have already been reporting seeing error messages or video streams freezing during playback.
The TV sets affected span the range of Bravia devices from smaller sets only 20in (50cm) across to those that span 89in (2.2m) and cost £25,000.
James O'Malley, writing on the Gizmodo gadget site, said the change proved there was just one rule when it came to buying a smart TV.
"Buy a dumb screen, and plug something smart into it," he said.
It was far better to use a Chromecast, Firestick or Apple TV box for smart TV services rather than rely on the in-built capabilities of a TV that are likely to be outpaced by changes in technology in a few years, he said.
In March this year, many smart TV sets lost the ability to use Skype as Microsoft ended support for the app.