Before
- Save instructions, files and Action schemas (instructions, files, actions).
- Write 10 real test questions and record current answers.
- Note who the GPT is shared with.
During
- Finish edits to the original before migrating, since it becomes read-only afterward.
- Move instructions first, then files, then Actions.
After
- Run your test questions and compare tone and accuracy.
- Test every Action end to end.
- Re-share and tell your users where the new version lives.
Source: OpenAI's Custom GPT retirement and migration FAQ. OpenAI says dates may change, so check the FAQ for your plan.
Keep reading
When are Custom GPTs being retired?OpenAI lists December 11, 2026 as the planned retirement date, subject to change.Will my Custom GPT stop working?Existing GPTs stay usable until the retirement date, then stop running.What happens to the original GPT after I migrate?It stays usable until retirement but becomes read-only.