Root Cause

In Strapi v5, API Token granular permissions are managed through the Admin RBAC permission system. The error:

error: adminUserOwner is required

is thrown by Strapi's admin permission validation schema (api-token.ts service). It occurs when Strapi attempts to register or update granular permissions for an API token without an active, verified Admin User context attached to the mutation request.

This typically happens in three scenarios in v5:

1. Dangling Token Creator Reference: The custom API token was created under an admin user that was subsequently deleted, edited, or originally seeded via a bootstrap script/CLI without an admin_user_owner ID.
2. Stale Admin Session / Token in Local Storage: After updating to Strapi v5.45.1, the cached Admin JWT in your browser session no longer satisfies the updated validation schema for the document service permission provider.
3. Uncompiled Content-Type Schema: The new content-type was created in the Content-Type Builder while the server was running, but the Admin RBAC permission registry hasn't recompiled the schema mapping.

How to Fix

Step 1: Re-authenticate to Refresh the Admin Context

Before editing the token:

1. In your browser, log out of the Strapi Admin panel (/admin).
2. Clear your browser cookies and localStorage for the Strapi host.
3. Log back in using your primary Super Admin credentials.

Step 2: Rebuild the Admin Panel & Restart the Server

If you created the content model recently, ensure Strapi recompiles the permission registry:

1. Stop your development or production process.
2. Clean cache and rebuild:

   npm run build
   # or yarn build / pnpm build

3. Restart the server:

   npm run develop
   # or npm run start

Step 3: Create a Fresh API Token (If the Token was Created Pre-v5.45)

If the specific custom token was created before the v5.45 update or via a migration:

1. Go to Settings → API Tokens.
2. Click Create new API Token.
3. Set the Type to Custom and assign the find and findOne permissions to your new content model.
4. Click Save.
   A freshly generated token will explicitly capture your current active Super Admin ID in the adminUserOwner relation, bypassing the missing context on the legacy token.

If refreshing your admin session or creating a fresh token resolves the permission error, please consider marking this response as the accepted answer!