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ERROR_INVALID_TIME
The supplied date or time is not valid for the operation.
ERROR_INVALID_TIME is Win32 error 1901 (0x76D). Windows time APIs commonly accept structured calendar fields, UTC or local values, file times, or service-specific schedules. The code indicates that the submitted value cannot be interpreted under the API’s rules. It does not by itself mean the system clock is inaccurate.
Examples of invalid time input
- month, day, hour, minute, second, or millisecond fields are outside their documented ranges
- the day does not exist in the specified month, including an incorrect February 29
- a local wall-clock time falls in a daylight-saving transition gap and has no valid mapping
- a conversion overflows the supported FILETIME or component-specific date range
- a parser accepted ambiguous or locale-dependent text and constructed inconsistent fields
Time context to record
Capture the original representation, parsed fields, timezone identifier, UTC offset, daylight-saving flags, source locale, parsing format, target API, and whether the value is intended as UTC, local time, or an elapsed duration. Avoid logging user-entered free text when it can contain sensitive content; structured numeric fields are usually enough. Include the operating-system timezone rules version for reproducible historical conversions.
How to isolate the invalid field
Validate every field before calling the operating-system API and test the calendar combination rather than only independent numeric ranges. Convert through a documented routine such as SystemTimeToFileTime and preserve its result. For local times near daylight-saving changes, evaluate ambiguous and nonexistent intervals explicitly.
Compare the same instant represented as UTC. If UTC succeeds but local conversion fails, investigate timezone rules rather than the hardware clock. If values originate on another platform or protocol, confirm epoch, unit, signedness, and endianness; milliseconds mistaken for seconds can exceed the accepted range.
Correction and API design
Reject or normalize invalid user input with a specific field message, use unambiguous formats, and store instants in UTC together with the intended timezone when wall-clock meaning matters. Do not silently clamp impossible dates because that can schedule work on the wrong day.
Developers should distinguish absolute timestamps from durations, use checked conversions, and add tests for leap years, minimum and maximum dates, and daylight-saving boundaries. A retry is useful only after the value or timezone context changes.
Difference from clock or synchronization failures
ERROR_INVALID_TIME is about the supplied value. Time-service synchronization errors concern obtaining or adjusting the machine clock even when the timestamp format itself is valid.
Example
A scheduler parses 2026-03-29 02:30 in a timezone where clocks jump from 02:00 to 03:00. Local conversion returns 1901 because that wall time never occurs. The UI asks the user to choose 03:30 or another valid instant instead of silently moving the job.
References
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