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ERROR_HV_INSUFFICIENT_BUFFER
ERROR_HV_INSUFFICIENT_BUFFER is HRESULT 0xC0350033 in the hypervisor output-buffer contract area of the Windows virtualization stack. It applies to one caller-visible buffer expected to receive hypervisor data.
What the code establishes
The selected operation can produce more data than fits in the supplied buffer. Preserve the required size, selector, structure version, and returned byte count before changing allocation logic.
This result belongs to the hypervisor facility rather than the higher-level VM management UI. The TLFS and WHP documentation provide the surrounding partition, message, memory, and virtual-processor model, but the first low-level operation and any nested status remain the authoritative incident evidence.
Neighboring result: This singular status differs from ERROR_HV_INSUFFICIENT_BUFFERS, which concerns an insufficient set of message buffers or descriptors.
Evidence that should survive remediation
| Evidence | Why it changes the diagnosis |
|---|---|
| Operation and selector | Record the query or hypercall and the exact data class requested. |
| Capacity fields | Keep allocated bytes, input Size field, output required size, and element count. |
| Versioned layout | Record architecture, packing, SDK header version, and reserved-field initialization. |
| Boundary result | Test exact-size, one-byte-short, and larger buffers with identical state. |
Controlled diagnostic sequence
- Use checked arithmetic when converting element counts to bytes.
- Honor any returned required-size value and rerun without changing the queried object.
- Verify native structure alignment in bindings and IPC wrappers.
- Do not treat a larger buffer as a permanent fix until the returned layout is parsed completely.
Test the smallest supported create, lookup, initialize, or resource request that preserves the named condition. In the result reproduction, change one count, identity, or lifecycle step at a time and capture the first host event before retry.
Read the comparison tests
| Control | Interpretation | Hold constant |
|---|---|---|
| Fresh owned object | A clean lifecycle changing this result implicates duplicate initialization, leaked ownership, stale lookup, or incomplete rollback. | Preserve request flags and topology while changing only object instance. |
| Same request on a compatible host | If it follows one host, compare resource limits, topology, build, and inventory before altering VM data. | Use the same request and leave virtual disks unchanged in the result comparison. |
| One operation parameter | Change one count, name, identity, or state transition. If it moves, the selected condition is causal rather than the VM as a whole. | Keep host build, VM ID, and returning operation fixed. |
Avoid the wrong recovery
Keep the hexadecimal result value and any nested hypervisor status. Higher layers can map distinct resource, buffer, message, or state failures to the same generic start or migration message.
Acceptance test
The fix is accepted when exact-size and growth cases succeed, the one-byte-short negative case still fails, and no data is silently truncated.
Technical references
- Microsoft Open Specifications: HRESULT values — used to interpret this result.
- Microsoft: Hyper-V architecture — used to interpret this result.
- Microsoft: Hyper-V TLFS — used to interpret this result.
- Microsoft: Hyper-V operational troubleshooting — used to interpret this result.
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