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OpenAI to Migrate Custom GPTs to Plugins; Custom Actions Will Not Be Converted Automatically
OpenAI plans to replace Custom GPTs with Plugins that include Skills and Apps. Affected Enterprise workspaces are scheduled to stop running legacy GPTs on December 11. The built-in migration handles only some settings, while Custom Actions must be rewritten as supported connectors or custom MCP servers.
OpenAI has updated its Custom GPT deprecation and migration documentation. Instructions, knowledge, and external tools previously bundled into a single-purpose chatbot will be reorganized as Plugins that can be used in ChatGPT and Codex workflows. Under the current Enterprise timeline, the migration interface is scheduled to begin rolling out on September 17, the creation of new Custom GPTs will end on September 25, and existing GPTs are scheduled to stop running on December 11. These dates may still change, and the functionality is not guaranteed to reach every workspace simultaneously.
The migration is not a one-to-one format conversion. A Custom GPT’s instructions will become a Skill within a Plugin, and connected Apps will be added to the Plugin. Reference files, templates, and tools will still require manual review. Conversation starters and existing chats may not be migrated, and the originally specified model will not be retained; Enterprise workspaces will instead use their default model. After migration, the legacy GPT will remain operational until its retirement date but will become read-only. Any subsequent changes must be maintained in the Plugin.
The most significant breaking point is Custom Actions. OpenAI explicitly states that actions integrating with external services through OpenAPI or similar mechanisms will not be converted automatically. Maintainers must switch to a supported connector or rebuild the integration as a custom MCP server. This involves more than rewriting the interface: teams must also reassess OAuth, tool permissions, data flows, action confirmations, and audit logs. Permissions to use, share, and publish a Plugin are managed separately. Users of the legacy GPT will not automatically receive access to the new Plugin or its Apps through link redirects.
OpenAI says the transition will ultimately affect all ChatGPT plans, but the specific public dates and administrative processes currently apply mainly to Enterprise. Complete details remain unavailable on whether individual Plus and Pro accounts will be able to create or edit private Plugins and how they can register custom MCP servers. Engineering teams should first inventory GPT owners, prompts and knowledge files, Custom Actions, dependent accounts, and test cases, then perform behavioral and permissions regression testing before the transition.