What does HRESULT 0x80040238 (TPC_E_QUEUE_FULL) mean?

TPC_E_QUEUE_FULL

Meaning and numerical form

TPC_E_QUEUE_FULL is HRESULT 2147746360 (0x80040238; signed -2147220936). AllStat records its meaning as “TabletPC inking error code. Queue is full”. In practical terms, it is returned when a Tablet PC stylus-data queue has reached capacity and cannot accept more input or plug-in output.

The severity bit in 0x80040238 is set, so this result is a failure result rather than a success or informational status. Its facility is 4 (FACILITY_ITF) and its low 16-bit code is 568 (0x0238). Those fields classify the value but do not identify the component instance, call, object or input that produced it.

Evidence to collect

A useful diagnostic record for this result includes the native API or interface method, component or CLSID, process and thread IDs, architecture, apartment where relevant, operation correlation ID, elapsed time, input identity, and the first state-changing event before failure. When diagnosing it, preserve IErrorInfo, an inner HRESULT, Win32 status, device event or provider message when available.

• Capture 1 for this HRESULT: input and output queue depth over time.
• Capture 2 for this HRESULT: per-plug-in processing latency and packet rate.
• Capture 3 for this HRESULT: UI-thread stalls, callback backlog and dropped-data policy.

Telemetry for this HRESULT should retain types, lengths, hashes, stable opaque identifiers and lifecycle generations while redacting content and credentials. This makes repeated incidents comparable without exposing ink content, packet data, account details or recognizer input.

Where the failure belongs

This result belongs to Tablet PC ink, stylus and recognition. Tablet PC APIs span device enumeration, RealTimeStylus packet queues, ink-object lifetime and recognizer-specific capabilities. The numerical facility does not identify which Tablet PC layer produced the result. The decisive condition is this: a Tablet PC stylus-data queue has reached capacity and cannot accept more input or plug-in output. Record the first native producer instead of relying only on a framework exception translated several layers later.

Do not infer from this result alone that reinstalling, rebooting or repeating the whole workflow is appropriate. Because it can cross process and language boundaries, its correction depends on the object identity, lifecycle generation, input and state at the first failing call.

Likely causes

• Possible cause 1 for this HRESULT: an asynchronous plug-in processes packets slower than they arrive.
• Possible cause 2 for this HRESULT: the UI thread blocks and stops draining the output queue.
• Possible cause 3 for this HRESULT: a plug-in expands data or recursively enqueues work.

Diagnostic sequence

1. Capture it at the first native return and identify the exact object and method.
2. Confirm that the observed path matches this condition: a Tablet PC stylus-data queue has reached capacity and cannot accept more input or plug-in output.
3. compare the live state with the method contract before changing configuration.
4. collect the code-specific evidence listed above and preserve any more specific preceding error.
5. change one evidence-backed cause at a time, then repeat the smallest operation that can prove the correction.
6. Add a regression check that distinguishes it from the related outcomes described below.

Correction and retry boundary

• Corrective action 1 for this HRESULT: remove blocking work from the real-time path.
• Corrective action 2 for this HRESULT: bound plug-in processing and move expensive analysis to a worker.
• Corrective action 3 for this HRESULT: define overload behavior that preserves responsiveness and data integrity.

Retry guidance for this HRESULT. Retrying the same packet is safe only if queue semantics and ordering are preserved; first restore consumption capacity and avoid unbounded producer loops. A retry must avoid this hazard: replay stale strokes, reorder stylus packets or reuse an invalid recognizer context. It must also preserve the evidence needed to locate the original producer of it.

Difference from nearby HRESULTs

TPC_E_OUT_OF_ORDER_CALL is a lifecycle sequencing error; it is a throughput and backpressure failure. Keep these outcomes separate in logs, exception mappings, user messages, dashboards and automated retry policy.

Developer and operational guidance

Code handling it should log the failed stage before cleanup, keep ownership and lifecycle transitions explicit, and avoid converting every failure into a generic message. Tests for this HRESULT should cover the primary cause, one adjacent HRESULT and the retry boundary so a future change cannot turn a deterministic contract failure into an uncontrolled loop.

Operational repair for this HRESULT should use supported device, Tablet PC component, recognizer and application lifecycle paths. Avoid unsupported configuration edits or component replacement unless evidence identifies that layer. Retain the original trace and a post-fix trace so the result can be attributed and the change reversed.

Practical scenario

A synchronous stylus plug-in performs network I/O on every packet and fills the queue; moving that work off the real-time path prevents it. The result scenario narrows the result to a reproducible contract boundary and supplies a concrete before-and-after test.

Official Microsoft references

• Microsoft: generic COM error codes
• Microsoft: StylusInput architecture
• Microsoft: StylusInput threading

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