BR-02 error
What this rule checks
Explanation
Every invoice must carry an Invoice number (BT-1) — the identifier that names this specific invoice, used for referencing, sequencing, and payment matching. Without it, the document has no way to be identified as a distinct invoice.
How to fix it
Populate the invoice number in the top-level ID element (UBL: cbc:ID directly under Invoice; CII: ram:ID under ExchangedDocument).
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