Migrated Custom GPTs fail to edit after plugin migration without backend ID

After migrating a Custom GPT to a plugin, the "Edit plugin" button in the UI no longer functions—Plugin Creator fails to publish updates because it lacks the required backend plugin ID. This error appeared on September 29, 2026, at 11:18 AM ET, with the exact message:

I couldn’t publish the update. I found #29’s current instructions, but Plugin Creator did not return the plugin ID needed to edit that existing plugin. I left it unchanged.

Please send the plugin’s link or backend plugin ID. Then I can add your mandatory passport input gate exactly as written while preserving the other instructions and files.

The migration itself completed without warnings—no issues with instructions, files, apps, or actions. The new plugin appeared in the Plugins view, and selecting it triggered Plugin Creator in Work mode, loading existing content. However, attempting any edit (such as adding a rule) left the publish button non-functional. The missing backend plugin ID, which should have been passed automatically during the "Edit plugin" workflow, blocked further changes.

The issue occurs on Chrome for Windows and affects the Custom GPT-to-plugin migration process. The migrated plugin remains functional but cannot be edited through the UI, leaving the original Custom GPT read-only.

Steps to reproduce

1. Open a Custom GPT in the web interface.
2. Click "Migrate to plugin" and confirm completion.
3. Locate the new plugin in the Plugins list and open it.
4. Select "Edit plugin" from the menu.
5. Plugin Creator loads the existing instructions but fails to provide the backend plugin ID.
6. Attempting to publish any edit triggers the error above.

Attempted fixes

• Refreshing the browser or reopening Plugin Creator did not restore the missing ID.
• Remigrating the plugin created a new instance, but the original remained locked.
• Network inspection revealed no plugin-ID parameter being requested during the "Edit plugin" action.

Impact and urgency

With 29 business-focused Custom GPTs dependent on precise updates, this breakdown prevents safe iteration. Users are forced to either accept a read-only plugin or rebuild from scratch—both impractical solutions. The root cause appears to be a missing reference to the backend plugin ID during migration, even after the Custom GPT becomes read-only.

Request for resolution

A fix is needed to ensure Plugin Creator receives the backend plugin ID when launched via "Edit plugin." Temporary workarounds, such as exposing the ID directly or allowing publishes without it for migrated plugins, could alleviate the immediate blocker. Until then, migrated plugins remain unusable for updates.