ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME - 15104 (0x3B00)
The RC Manifest has invalid ultimatefallback name.
Updated: Feb 21, 2026
Technical Meaning
This error code indicates that the Resource Compiler (RC) manifest used in a localization process contains an invalid ultimate fallback name. The ultimate fallback name is crucial for determining the default language or resource set when multiple languages are available.
Error Details
The RC Manifest, which is part of the Windows API and used to manage resources such as strings, icons, and other localized data, requires a specific format for its ultimate fallback name. If this name is not correctly specified, the system cannot properly resolve the default resource set, leading to this error.
Usage Context
This error typically occurs during the localization process of Windows applications or components. It can be encountered when attempting to load localized resources from an application that has been compiled with a manifest containing an invalid ultimate fallback name.
Developer Interpretation
Developers should ensure that their RC manifests are correctly formatted and contain valid ultimate fallback names. This is particularly important for applications that support multiple languages or regions, as the ultimate fallback name plays a critical role in determining the default resource set when no specific localization is available.
Related Errors
- ERROR_MUI_FILE_NOT_FOUND (1269)
- ERROR_MUI_INVALID_LCID (15073)
- ERROR_MUI_STRING_NOT_FOUND (1400)
FAQ
Q: What does the ultimate fallback name do?
A: The ultimate fallback name is used to specify the default language or resource set when multiple languages are available. It helps in resolving resources when no specific localization is requested.
Q: How can I avoid this error?
A: Ensure that your RC manifest includes a valid ultimate fallback name and that it adheres to the required format specifications.
Summary
The ERROR_MUI_INVALID_ULTIMATEFALLBACK_NAME (15104) indicates an issue with the RC Manifest's ultimate fallback name. Developers should verify the correctness of their manifests to prevent this error from occurring.