OpenAI shut down the Assistants API on August 26, 2026, and AI Engine removed the Assistants module in version 3.7.5. Assistants no longer work in AI Engine.

What to use instead

Most people used Assistants for a chatbot that answers from their documents. You can do the same with Knowledge and an OpenAI Vector Store environment: upload your files, select the environment in your chatbot, and it works with the regular OpenAI models (and with Claude, Gemini and other providers too).

If your assistant relied on custom actions, have a look at function calling, which lets your chatbot call your own code.

If the module is still switched on

On sites that had Assistants enabled before the update, the option still shows in the Modules tab (in the Deprecated section), only so you can turn it off. Switch the chatbots that were in Assistant mode back to Chat mode, pick a model, then disable the Assistants module.