Prepare for the Retirement of GPT-4.5 and o3 Models
Update your workflows before the 2026 model sunset dates.
Transition your prompts from retired models (o3, GPT-4.5) and the 'canvas' feature toward GPT-5.5's new inline writing/code blocks.
The Scenario
You have a recurring workflow or a Custom GPT that currently relies on GPT-4.5 or the 'canvas' interface for code and writing.
Before & after
Users manually checking for model availability and rewriting prompts for older models like o3 or 4.5 could spend 30–45 minutes troubleshooting broken custom GPTs.
Migrate custom workflows to GPT-5.4/5.5 thinking or instant blocks in under 5 minutes to avoid disruption.
The Prompt
Review my current workflow or prompt: [PASTE_PROMPT]. Since GPT-4.5 and o3 are being retired, optimize this prompt for GPT-5.5 Instant using writing blocks instead of canvas.
OpenAI has set hard retirement dates for o3 (August 26, 2026) and GPT-4.5 (June 27, 2026) in ChatGPT. Furthermore, 'canvas' is being replaced by writing and code blocks in newer models.
Source
Model Release Notes | OpenAI Help Center"canvas will no longer be available in GPT-5.5 Instant... Writing and coding functionality is now supported directly in chat responses."