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| WEB_E_INVALID_JSON_NUMBER | E_INVALID_PROTOCOL_OPERATION |
WEB_E_JSON_VALUE_NOT_FOUND
WEB_E_JSON_VALUE_NOT_FOUND (0x83750009) identifies requested JSON member or value absent. The JSON text can be parsed, but lookup for a required property, array position, or projected value returns no match. Record network reachability, HTTP status, and parser acceptance as separate layers.
Record the lookup contract
| Lookup fact | Reason |
|---|---|
| Property name | Keep exact case and Unicode spelling. |
| Container path | Identify every object and array step leading to the lookup. |
| Requiredness | Separate optional absence from a mandatory contract violation. |
Typical causes
- The producer omitted null or default-valued members.
- Client and server use different field names or contract versions.
- The code queries the wrong object after traversing an array or nested response envelope.
High-value tests
- Log the available sibling property names safely
- Query a known mandatory field in the same object
- Test absent, explicit null, and empty string as separate cases
Close the issue
The corrected client follows the actual JSON path and handles optional absence explicitly. A regression sample should retain an absent-member case rather than treating every lookup as guaranteed.
Missing is not JSON null
Object member names are case-sensitive, array indexes are positional, and an explicit null value is still present. Record the complete lookup path and the node type reached at each segment; otherwise a wrong parent object can be mistaken for one absent leaf member.
Before changing configuration
- Confirm this is the first failure rather than a cleanup result
- Preserve the exact input or object state selected at the failure
- Identify limits, negotiation choices, or lifecycle transitions immediately before it
- Design a one-variable experiment instead of enabling broad retry or compatibility behavior
Acceptance evidence
Close the result investigation only when the original supported operation succeeds repeatedly, an invalid control still fails, and resource ownership remains correct; success on different data or another endpoint is not equivalent evidence.
Representation pipeline
| Stage | Evidence to retain |
|---|---|
| Producer model | Serializer, contract revision, omission, ordering, escaping, and numeric options |
| Transport bytes | Content type, charset, content encoding, declared length, and parser-visible bytes |
| Parser state | Offset, line or token path, expected construct, and actual construct |
| Projection layer | Schema, object mapper, or lookup converting XML or JSON into fields |
Normalization risks
Pretty-printing, reserialization, charset conversion, or browser copying can erase the condition producing this result; hash the original body, apply deterministic redaction, and retain both received and decompressed forms when content encoding is involved.
Focused regression corpus
- A minimal document containing no unrelated members
- A valid document at the nearest relevant boundary
- A contract-version variant showing strict or forward-compatible behavior
- A transport variant proving framing and character decoding are not hidden causes
Fix ownership
| Layer | When it owns the correction |
|---|---|
| Transport | Change framing, decompression, or character decoding only when captured bytes prove this layer altered the representation |
| Parser | Change syntax handling only when the raw token or markup violates the selected format |
| Projection | Change requiredness, path, ordering, or value conversion only after parsing succeeds |
| Producer | Correct serialization when the emitted representation contradicts the published contract |
Technical references
- Microsoft Open Specifications: HRESULT values
- Windows Web Services overview
- Windows.Data.Json API
- RFC 8259: JSON
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