This user is not approved for the webmaster program
Admin websites API returned 400 This user is not approved for the webmaster program.
Why this happens
Admin action targeted a user without webmaster approval. Site program may be on. Distinct from program-disabled messages.
Diagnose and fix
1. Admin → Users — enable/approve webmaster for that user (Affiliate / webmaster / reseller flags on a user).
2. Optionally Approve webmaster on register for future signups.
3. Retry the websites admin action.
4. See Webmaster websites approval.