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ERROR_MCA_EXCEPTION
a thread is being dispatched with a machine check architecture exception.
ERROR_MCA_EXCEPTION means that this condition Machine Check Architecture reports processor-detected hardware faults such as cache, bus, memory-controller, or interconnect errors. This result indicates that Windows is delivering or recording such an exception in the execution path of a thread.
Where the result appears
- hardware error handling and WHEA diagnostic paths.
- debugger output after a processor machine-check event.
- virtualization hosts exposing a hardware exception to a guest or management component.
- low-level services that translate an exception into a Win32 code.
What the result tells you
The value identifies a specific Windows state, but it does not by itself identify the component that introduced that state. Preserve the original this result value, the API or subsystem that produced it, and the object being operated on. A wrapper that replaces it with a generic exception or Boolean failure removes the distinction needed to choose the correct recovery path.
Diagnostic evidence to collect
- the machine-check bank status, address, miscellaneous register, and processor number.
- WHEA error record severity and component classification.
- CPU microcode, BIOS/UEFI, chipset firmware, and overclocking state.
- temperature, power, ECC, and recurrence data around the same timestamp.
Correlate the result evidence on one timeline. The first event that changes the state associated with this result is usually more valuable than later retries returning the same code. Record process and thread identity, session, timestamp, API parameters, and the immediately preceding successful operation.
Handling and recovery
Stop treating the affected execution as trustworthy until hardware health is assessed. Remove overclocking, update firmware when recommended by the system vendor, run platform diagnostics, and replace the component identified by repeated records. Production systems should be drained if uncorrectable events recur.
Retry after it only when the evidence shows that an external condition can change. When it is caused by malformed input, revoked authority, unsupported state, hardware damage, or an offline maintenance requirement, an unchanged retry adds noise and can overwrite the earliest useful diagnostics.
Common misinterpretation
An MCA exception is not a normal software exception caused by bad input. Application-level catch-and-retry logic cannot repair a failing processor cache, memory controller, or bus.
Guidance for developers
Keep it in its Win32/LRESULT domain in structured telemetry. When converting it to an HRESULT, exception, RPC response, or JSON field, retain the source domain and numeric value alongside the human-readable text. Do not branch on the localized message string for this Win32 error.
A test should construct the specific state, assert the exact result, and verify that partial resources are released. The recovery test for this Win32 error should prove that the operation is either deferred until a measurable state change or fails without an uncontrolled retry loop.
References
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