These conditions were checked October 23, 2026. An older tutorial saying that any Plus subscriber can open the builder does not describe the current rule.
If Create is missing, check the account first
Confirm the active workspace before troubleshooting the browser. A personal account's missing creation control is an eligibility restriction. Existing GPTs can still be used, and editing previously created GPTs depends on plan and permissions. Current GPT troubleshooting
OpenAI is planning custom-GPT retirement, with December 11, 2026 named for affected Enterprise workspaces; other plans should check their account notices. Review the current notice and replacement options before investing in a new reusable workflow. Retirement notice
Do not buy a personal subscription on the assumption that it will restore new GPT creation. If your work only needs a reusable response preference, custom instructions may address that narrower task without creating a GPT.
Give an eligible GPT one clear job
Consider a fictional internal assistant called “Workshop brief reviewer.” Its job is to check an event brief for missing operational details. It does not book rooms, approve budgets, or contact speakers.
In the builder, you can describe the job conversationally or configure the fields directly. Put behavior in Instructions and reference documents in Knowledge. Builder and configuration
This original instruction example keeps the scope visible:
Review workshop briefs for the organizer.
When a brief is supplied:
1. List the stated date, venue, intended audience, and responsible person.
2. Mark any missing item as "Not supplied."
3. Identify contradictions using the wording in the brief.
4. Return a short list of questions the organizer must resolve.
Do not invent bookings, approvals, attendance figures, or deadlines.
If reference material is attached, distinguish it from the current brief.
The instruction defines an inspection task. A room handbook would supply reference information; it would not replace the instruction telling the assistant what to inspect.
Test a missing fact and a contradiction
Use a small fictional brief before trying a real internal document:
The workshop is planned for November 18.
The draft invitation says November 19.
The audience is new volunteers.
The venue and responsible organizer have not been supplied.
A useful response flags the conflicting dates and leaves the venue and organizer unresolved. Choosing one date or inventing a room fails this test. Run the case in Preview and inspect the actual response against those checks.
OpenAI recommends testing in Preview and making smaller changes when instructions behave inconsistently. Clear, text-forward reference files are easier to use than complicated layouts. Instruction and knowledge troubleshooting
Revise the instruction when the test exposes a problem, then run the same case again. Before using or sharing the GPT, review the workspace's allowed access and keep only the reference material its intended users should receive.