GPT-4.5 Formally Retired
On June 27, GPT-4.5 was formally retired from ChatGPT. This wasn't a spur-of-the-moment decision: OpenAI announced a 30-day sunset period back in the May 28 release notes, and this day was exactly when it expired. After retirement, conversations users had opened with GPT-4.5 auto-migrate to the corresponding GPT-5.5 model, with no manual action needed.
A Routine Metabolic Cycle
Taken alone this isn't big news, but it's a footnote to OpenAI's product-line convergence: as the GPT-5.5 series (including Pro, Instant, and other variants) settles in, earlier generations are gradually cleared off the menu, consolidating the choices and freeing up compute for new models. For ordinary users it's basically imperceptible—the migration is automatic. What really needs attention is developers who make a living on the API: once a model enters the sunset period, a model name hardcoded in the code (like `gpt-4.5`) will stop working when it expires. Making the model version configurable and watching the retirement schedule in the official release notes is basic hygiene for avoiding an interface suddenly erroring one day. This smooth migration is also a reminder—don't treat any specific model as a permanent dependency.
via: OpenAI Release Notes