0300·A numeric value is invalid
Data formatCommon
What this means
Every numeric field must carry an actual non-negative number. Optional fields are optional in the sense that they may be zero — not in the sense that they may be omitted or null. The response usually names the offending field and line.
Why it happens
- An optional field such as discount, extra tax, or further tax was left null rather than set to zero.
- A number was serialised as a quoted string.
- A credit adjustment produced a negative value.
- An empty string was submitted where a value was not applicable.
How to fix it
- 1Default every optional numeric field to zero rather than null.
- 2Serialise numbers as JSON numbers, not strings.
- 3Handle reductions through credit notes rather than negative line values.
- 4Read the error text — it identifies which field and which line failed.
How Ordyoo handles this
The payload builder defaults all optional numeric fields to zero and is covered by tests running against a specification-accurate local mock, so null leakage is caught before it reaches FBR.
Scenarios where this appears
Sandbox scenarios that commonly produce 0300.
Related errors
Stop debugging FBR payloads by hand
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