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ERROR_INVALID_AT_INTERRUPT_TIME
What ERROR_INVALID_AT_INTERRUPT_TIME means
The requested exclusive semaphore operation is invalid at interrupt time or from an execution context that cannot wait. This is a context-contract error. A routine attempted synchronization that may block while running at an interrupt-sensitive level or equivalent non-waitable context. It is most relevant to low-level, legacy, or emulated execution environments.
Common causes
- A callback running at elevated execution level calls a potentially blocking routine
- Driver or compatibility code performs user-mode style synchronization in an interrupt path
- A helper function is reused without documenting its waitability requirements
- Deferred work was not queued before entering the blocking section
How to investigate
- Capture the execution level or callback type at the failing call
- Trace the call chain to find the first routine that introduced a waitable operation
- Separate interrupt-time work from deferred worker-thread processing
- Use verifier or checked instrumentation appropriate to the component type
Developer guidance
Keep interrupt-sensitive paths bounded and nonblocking. Record minimal state, queue deferred work, and perform semaphore acquisition from a context where waiting is legal.
Administrator and support guidance
This result normally requires a code correction. Restarting can clear the immediate incident but cannot make an invalid execution context safe.
How this code differs from related results
The code is about where the operation runs, not whether the semaphore name, handle, or access rights are valid.
Evidence worth collecting
For ERROR_INVALID_AT_INTERRUPT_TIME, begin the trace at the operation where a callback running at elevated execution level calls a potentially blocking routine. Preserve the exact API boundary, numeric result, process and thread identifiers, relevant object state, and the component version. The first verification point should be to capture the execution level or callback type at the failing call. This evidence distinguishes the specific this result contract from a later secondary failure.
Recovery and verification
Recovery for it should address the observed condition rather than merely retrying the same call. After the change, reproduce the scenario in which a callback running at elevated execution level calls a potentially blocking routine, then confirm that the intended operation completes and that cleanup returns all associated resources. Also verify that the next repeated operation follows the same successful path without increasing the resource class implicated by this result.
When to escalate
Escalate this result with a minimal reproduction focused on the failing pipe or compatibility boundary. Include the operating-system build, binary architecture, runtime or compatibility-layer version, the exact input values, and a timestamped trace showing a callback running at elevated execution level calls a potentially blocking routine. For the result escalation record, note whether changing concurrency, object lifetime, target process, module set, or endpoint location alters the result.
References
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