Custom GPTs Retire on December 11, 2026: How to Migrate to ChatGPT Plugins (and What Happens to Gemini Gems)

When I opened ChatGPT on 19 October 2026, the My GPTs page had a new banner across the top: "GPTs will be retired on December 11. To keep using your GPTs, migrate them to a plugin by December 11." The GPT store shows a softer version: GPTs that their creators migrate "will remain available as plugins after December 11."

If you built a GPT, the clock is running. If you only use other people's GPTs, there's nothing for you to click. Whether a GPT survives depends on its creator migrating it.

The dates

• 11 September 2026: OpenAI announced that plugins replace custom GPTs.
• Now: you can still create GPTs on most accounts, but trying to create one offers "Create Plugin Instead". Trade press reports that creating new GPTs ends on 26 October for Enterprise workspaces. OpenAI's FAQ says dates "may change".
• 11 December 2026: custom GPTs are retired. They stop running and leave the GPT directory.
• 11 February 2027: Enterprise customers with an approved deferral can keep GPTs until then.

Related reading: How to Stop ChatGPT, Claude, Gemini and Copilot Training on Your Data (and Check It Stayed Off) · How to Put a Hard Spending Cap on AI Agents (OpenAI, Claude, Bedrock, OpenRouter) Before an Overnight Run Costs You Thousands

What carries over, and what doesn't

OpenAI's migration guide is clear on most of this:

One more behaviour change matters more than any line in that table. A GPT applied its instructions to every message. A plugin's skill runs when ChatGPT decides it fits the task, or when the user picks it with @. OpenAI's own guide says an installed plugin "won't run on every request". If your GPT depended on always behaving a certain way, test that first.

How to migrate, step by step

1. Back up first. Copy your instructions into a text file, download your knowledge files, write down your conversation starters, and screenshot the configuration of any custom actions (endpoint, auth type, schema). None of this costs anything, and the starters and actions won't come across on their own.
2. Open My GPTs, find the GPT under Created by me, and choose Migrate to plugin. The GPT has to be published, and you can only migrate GPTs you own.
3. Test it. Try a couple of familiar tasks and one hard case. Check that the right skill gets picked, that the output format matches, and that any apps it needs are available. OpenAI's advice: if a capability is missing, keep using the old GPT until you have a tested alternative.
4. Share it again. The plugin is private to start. On a workspace you need the Share plugins permission to share it, and Publish plugins to workspace to list it. Sharing and installing are separate steps: people you share with still have to install it unless an admin does it for them.
5. Tell your users. Send the new link, explain what's different (for example, using @ to call it), and name someone who'll maintain it.

After migration the original GPT becomes read-only and keeps working until 11 December.

Two practical notes:

• Builders have reported knowledge files that worked in a GPT being rejected during migration because plugins have different file limits. Check that every file made it across.
• Converting a GPT doesn't use credits, but on credit-based plans, editing a plugin afterwards does.

Workspace admins can migrate in bulk: in ChatGPT Work, type @, choose ChatGPT Admin, run the GPT report and ask it to migrate selected GPTs. It asks for confirmation first.

Replacing a custom action

This is the part that takes real work. A custom action called your API from an OpenAPI schema. In a plugin, that becomes either:

• An existing app that already offers the read or write action you need. Check the app directory before building anything.
• A custom MCP server that exposes your API as tools. OpenAI's Codex docs have a section on "Replacing a GPT custom action". If your action was a simple GET or POST to your own backend, an MCP server is usually a thin wrapper around the same endpoints. The work is mostly authentication and hosting, not the logic.

Plugins are shared between ChatGPT and Codex, which is a bonus: the same MCP server can serve your coding workflow too.

If you only use other people's GPTs

You can't migrate a GPT you don't own. If you rely on one:

• Check whether the creator has posted about a plugin version.
• Save your own copy of anything important you did in it. Past chats aren't moved into any plugin.
• Look in the plugin directory for an equivalent.

Gemini Gems are going the same way

Google is making a parallel change. On 30 September 2026 it announced that skills replace Gems.

• A notice in the Gemini app says that starting 17 November 2026, Google will automatically begin migrating Gems to skills, and Gems keep working until they're migrated.
• Gems made on Workspace business, enterprise and non-profit accounts reportedly stay until March 2027, and education accounts until June 2027.
• Android Authority found code suggesting you can no longer create or edit Gems from 13 October. Google hadn't confirmed that date in anything I could find.
• Reports also conflict on whether creating skills needs a paid Google AI plan. Check Google's help page before relying on either version.

Unlike OpenAI's, Google's migration is automatic, but the same advice applies: copy your Gem instructions somewhere safe now.

Last checked: 19 October 2026. I'll update the dates if OpenAI or Google move them.

Sources

• OpenAI Help: Custom GPT retirement and migration FAQ
• ChatGPT docs: Migrate custom GPTs
• Virtualization Review: OpenAI to retire custom GPTs, replace them with plugins (28 Sep 2026)
• Visual Studio Magazine: Plugins for ChatGPT and Codex (28 Sep 2026)
• Notebookcheck: Gemini starts turning Gems into skills on November 17
• Android Central: Google's timeline to phase out Gems
• PCWorld: Gemini skills replace Gems