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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. The built-in message names the immediate result; the useful custom context is the exact boundary: one caller-visible buffer expected to receive hypervisor data. Record the first returning operation and host-side event before a management layer retries or translates it.
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 boundary.
Neighboring result: This singular status differs from this resultS, 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. |
Preserve identifiers and counts without dumping guest secrets or unrelated memory. Useful this result timestamps include the last successful operation, first failure, any automatic retry, and the object-generation change that followed.
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
Across these controls for it, preserve one caller-visible buffer expected to receive hypervisor data as the boundary under test.
| Control | Interpretation | Hold constant |
|---|---|---|
| Fresh owned object — this result | 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 generation. |
| Same request on a compatible host — it | 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 — it | Change one count, name, identity, or state transition. If it moves, the selected boundary is causal rather than the VM as a whole. | Keep host build, VM ID, and returning operation fixed for it. |
Avoid the wrong recovery
A restart may release internal objects and make it disappear while erasing registration, ownership, resource-count, or teardown evidence. Capture the first result event chain before recovery.
Keep the hexadecimal it 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. Repeat the original operation under the original supported conditions and retain one deliberate negative control. A management command succeeding on a different object is not sufficient to close this incident.
Technical references
These sources define it and the public Hyper-V architecture surrounding the internal state. They do not create a public user-mode VID API for the named object.
- Microsoft Open Specifications: HRESULT values — used to interpret the boundary.
- Microsoft: Hyper-V architecture — used to interpret the boundary.
- Microsoft: Hyper-V TLFS — used to interpret the boundary.
- Microsoft: Hyper-V operational troubleshooting — used to interpret the boundary.
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