Hi,

This error means that Odoo could not find a Sales Journal configured for your company.

• Go to Accounting → Configuration → Journals
  Make sure you’re in the right company (multi-company setups often cause this). Check if there’s a journal with:
  Journal Type = Sale
  Company = your company
• If no Sales Journal exists:
  Click New (Create)
  Example setup:
  Journal Name → Customer Invoices
  Journal Type → Sale
  Default Debit Account → Accounts Receivable
  Default Credit Account → Accounts Receivable
  Company → select your company
• If one exists but still failing:
  Open it and confirm the Company is set correctly.
  If you’re working under a specific company, you won’t see journals from another.

Hope it helps.