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TAPI_E_REQUESTOVERRUN
The request queue is already full
TAPI_E_REQUESTOVERRUN is HRESULT 2147745829 (0X80040025) from Tapi3err.h. AllStat describes it as “The request queue is already full.” The result normally appears while submitting requests faster than the registered recipient can consume them. Its useful interpretation is precise: the Assisted Telephony request queue is not valid for the exact provider, object, method, or lifecycle state that consumed it.
Code-specific check: The defining condition is “The request queue is already full.” Confirm that condition at the producing API before applying recovery intended for a neighboring result.
API and object context
- This result belongs to TAPI 3 address, call-control, phone, terminal, media-provider, request, or call-center processing.
- Associate this result with one concrete native method among ITTAPI, ITAddress, ITBasicCallControl, ITCallInfo, ITStream, ITTerminal, ITPhone, provider events, and Assisted Telephony.
- Before releasing objects after this result, retain provider identity, object generation, current state, requested transition, and the event sequence surrounding submitting requests faster than the registered recipient can consume them.
When the application constructed the Assisted Telephony request queue, it usually calls for caller-side validation. When enumeration or an event supplied it, it more often points to stale lifetime, provider replacement, device removal, configuration drift, or cross-session reuse. The ownership distinction for this HRESULT prevents a broad repair from masking the real defect.
Why this condition occurs
- It can occur when the caller supplies a malformed, unsupported, stale, or out-of-scope Assisted Telephony request queue.
- It can also indicate that the Assisted Telephony request queue belonged to another address, call, device, provider generation, user session, or COM object.
- An asynchronous event can produce it when removal, disconnect, cancellation, reinitialization, or a state transition occurs after validation.
- A wrapper can trigger it by converting an enumeration, identifier, duration, structure size, encoding, or ownership rule incorrectly.
Choose among those branches only after comparing the failed Assisted Telephony request queue with live capabilities or objects obtained from the same provider generation. A well-formed value can still be invalid because its scope, owner, state, or lifetime no longer matches the operation.
Telemetry for a useful incident
- Record it, 0X80040025, the native method, operation ID, elapsed time, process and thread IDs, application build, architecture, and COM apartment.
- capture queue capacity, producer rate, oldest request age, recipient process health, request mode, and retry count.
- Keep provider version, address/call/phone/terminal identities, current state, requested state, object generation, and the first lower-level error that preceded it.
- Redact telephone numbers, credentials, recordings, user-user data, and directory attributes from it telemetry while retaining lengths, types, hashes, ranges, capability flags, and opaque correlation identifiers.
A useful incident can answer whether the Assisted Telephony request queue came from configuration, enumeration, user input, cached state, or a provider callback. The result record should also show whether the operation succeeds with a newly enumerated object or freshly validated value.
How to isolate the fault
- Capture it at the first native return and identify the exact method used for submitting requests faster than the registered recipient can consume them.
- Validate the Assisted Telephony request queue without silently correcting it; check type, size, range, encoding, identifier scope, ownership, and lifetime as applicable.
- Enumerate current provider capabilities or objects and compare them with the Assisted Telephony request queue rejected by it.
- Reconstruct the event timeline before it to find removal, disconnect, cancellation, service restart, provider reinitialization, or another state transition.
- Reproduce it with one object and one operation, then vary only the suspected field or state while tracking partial output and side effects.
Correction strategy
The evidence-based correction for this HRESULT is to apply backpressure, deduplicate repeated requests, and restore the request handler before accepting more work. After it follows a provider, device, service, or configuration change, obtain a fresh object because an old interface or opaque identifier may remain invalid after recovery.
An automatic retry of it needs a bounded count, an idempotency rule, and a measurable changed-state predicate. User-visible handling of it should describe the actionable condition—invalid data, wrong state, missing resource, unavailable service, or policy refusal—rather than displaying only the HRESULT.
Representative scenario
For example, a browser plug-in repeatedly submits the same dial request while the handler is hung; rate limiting prevents another queue overrun The application should log the failed Assisted Telephony request queue, provider and object generation, native method, and state-changing event, then verify recovery with a newly obtained object instead of reusing the instance that returned it.
Do not confuse it with
TAPI_E_REQUESTQUEUEFULL also reports queue saturation; preserve the exact API path because the two constants belong to different request boundaries Keep that distinction when building dashboards and exception mappings for this HRESULT; otherwise input defects, lifecycle races, capacity limits, service outages, and final call outcomes collapse into one misleading category.
Developer and administrator actions
Operational repair for this HRESULT should target only the component identified by evidence: the Telephony service, service provider, COM server, device, configuration record, application package, or remote system. Copying arbitrary DLLs or broadly deleting registration data can create additional failures without correcting the original Assisted Telephony request queue.
References
- Microsoft: TAPI_E constants — official Microsoft documentation used to interpret it.
- Microsoft: TAPI 3.1 Reference
- Microsoft: Telephony API interfaces
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