Custom GPTs retire on December 11: actions and sharing don't transfer. A migration checklist
OpenAI retires custom GPTs on December 11, 2026. Enterprise workspaces with an approved deferral have until February 11, 2027. The migration path is the “Migrate to plugin” option.
What moves, and what doesn’t
According to OpenAI’s retirement and migration FAQ:
| Part of the GPT | After migration |
|---|---|
| Instructions | Become a skill on the plugin |
| Knowledge files | Become reference files |
| Connected apps | Carry over |
| Custom actions | Do not transfer. Rebuilding them “may require a custom MCP server and technical setup” |
| Selected model | Does not carry over |
| Sharing settings | Do not transfer |
For a GPT that is only instructions and files, the built-in migration is often enough. The work is in everything else.
What workspace owners are running into
From the OpenAI community forum since late September:
- Migrated GPTs coming out private to the person who migrated them, with plugin sharing disabled even for the workspace owner. Other posters reported this was fixed around October 8, but permissions still have to be set again.
- A team member migrating a shared GPT without telling its owner, so the whole workspace switched to a copy nobody had checked.
- A small business’s email agent, built as a GPT with an action calling an authenticated webhook, losing the action in migration, with no protected place in the plugin to store the key.
None of these are exotic. They are what happens when a migration is done one click at a time by whoever gets there first.
A migration checklist
- Inventory every GPT. For each one: owner, who uses it, instructions, knowledge files, connected apps, custom actions and the model it was set to. Export the instructions somewhere safe now.
- Triage. Decide for each GPT whether to migrate it, merge it with another, or let it retire. Most workspaces have GPTs nobody uses.
- Save a baseline. Run 10 to 20 real prompts through each GPT you are keeping, and save the answers. After December 11 you can’t.
- Assign one owner per GPT. One person migrates each GPT, and everyone else waits. This prevents the unannounced migrated copy.
- Migrate instructions and files. Use the built-in migration for this part.
- Rebuild custom actions properly. Rebuild each one as an MCP server or an authenticated webhook, with credentials stored outside the instructions. An API key pasted into a skill is a leak waiting to happen.
- Run the parity test. Run the saved prompts against the plugin and compare. Because the selected model doesn’t carry over, expect some differences, and decide which ones matter.
- Set sharing and tell staff. Set permissions deliberately, then send one short note saying what changed and where to find it.
How long it takes
For a workspace with three GPTs, one of them with a custom action, this is about three working days, most of it spent on the action and the parity test. Our Custom GPT migration package is $1,200 for up to three GPTs, plus $400 for each GPT with a custom action. It starts with a $400 inventory and plan, which is also the first step of the checklist above.