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ERROR_INVALID_FLAGS
invalid flags.
ERROR_INVALID_FLAGS means that a flags argument contains unsupported bits or a combination that the called API does not accept. In this case, the decisive context is Win32 calls that accept bitwise option masks, together with the exact hexadecimal mask and symbolic flags the caller intended.
Where the result appears
- Win32 calls that accept bitwise option masks.
- version-dependent filesystem, process, networking, security, or UI features.
- language bindings that map enums to native flags.
- configuration values persisted by an older or newer product version.
Typical causes
- one or more unknown bits are set.
- two individually valid options are mutually exclusive.
- a flag is valid only with another parameter or object type.
- headers and runtime versions do not support the same option set.
Evidence to collect
- the exact hexadecimal mask and symbolic flags the caller intended.
- API version, operating-system build, SDK/header version, and architecture.
- related parameters whose values constrain legal flag combinations.
- the code path that assembled the mask, including defaults and configuration input.
For this condition, begin the investigation with the exact hexadecimal mask and symbolic flags the caller intended. Correlate it with API version, operating-system build, SDK/header version, and architecture and check whether one or more unknown bits are set. Capture the original this result immediately after the failing call so later cleanup does not replace the thread-local error value.
Handling and recovery
Validate masks against the documented allowed set before calling the API. Reject unknown configuration bits explicitly, and negotiate optional capabilities rather than assuming a new flag works everywhere. When falling back, remove only the unsupported feature and keep security-relevant semantics intact.
Any retry policy for this Win32 error should be tied to evidence that two individually valid options are mutually exclusive has changed. Before another attempt, verify related parameters whose values constrain legal flag combinations. If headers and runtime versions do not support the same option set still applies, stop the retry sequence and preserve the first diagnostic event.
Common misinterpretation
A nonzero flags value is not inherently invalid. The defect is an unsupported bit or combination, not simply the presence of options.
Guidance for developers
When surfacing this result through another layer, retain its Win32 domain, numeric value, and the operation described by version-dependent filesystem, process, networking, security, or UI features. A useful telemetry record also includes the code path that assembled the mask, including defaults and configuration input. For a-related handling, decisions must use the numeric value and documented API contract rather than localized wording.
A focused test should reproduce the condition in which a flag is valid only with another parameter or object type, assert this result, and confirm that the program releases resources associated with language bindings that map enums to native flags. The recovery test should also verify that the exact hexadecimal mask and symbolic flags the caller intended is refreshed before the operation resumes.
References
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