What does Windows error code 15104 (ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME) mean?

 
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ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME

ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME indicates that the resource configuration has an invalid fallback language name. The fallback is used when no resource file matches the requested UI language.

What to check for ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME

  • Verify the fallback locale written into the MUI resource configuration.
  • Ensure that the corresponding fallback resource file is actually included in the installation.
  • Keep the fallback definition synchronized with the language-neutral binary and all localized resource files.

Microsoft: MUI Resource Management

Microsoft: Deploying multilingual resources

Microsoft: About Multilingual User Interface

Where ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME is returned

ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME is Win32 system error 15104 (0x00003B00) from winerror.h. AllStat describes it as “The RC Manifest has invalid ultimatefallback name.”. For ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME, the code is useful only together with the API that failed, because multiple Windows components can reuse system-error values while imposing different retry and cleanup rules.

Diagnostic sequence for ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME

  • Call GetLastError immediately after the failing API and save ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME, the function name, all relevant flags, and the target path, handle, service, device, account, or policy object.
  • Capture the component log that owns the mui / ultimatefallback / name operation and retain the original numeric value before a framework converts it to an HRESULT or exception.
  • For ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME, compare preconditions with the API documentation and reproduce with a minimal request before changing system-wide configuration.

Retry ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME only after the resource or state named in “The RC Manifest has invalid ultimatefallback name.” has changed. For ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME, for invalid parameters, unsupported formats, missing objects, policy restrictions, and access failures, correct the input or configuration instead of immediately repeating the same call.


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