dotnet/runtime · error · Error

Locale info for locale=

Error message

Locale info for locale=${localeName} is null or empty.

What it means

Thrown by SystemJS_GetLocaleInfo in globalization-locale.ts when Intl.DisplayNames produced empty/undefined values for both LanguageName and RegionName, so the joined result (separated by ##) is empty. This means the ICU/display-names data could not produce any string for the requested locale. Like error 21 it is caught locally and forwarded to managed code as an error string without aborting.

Solutions

1. Ship the full ICU data archive (icudt.dat) or the shard that covers the requested locale.
2. Switch globalizationMode to All, or use a Custom ICU archive that covers the cultures you query.
3. Validate the locale against navigator.languages / a known list before requesting display names.

Example fix

// before: only EFIGS shard shipped, querying ja-JP fails
// dotnet.native.js config: resources.icu = [{ name:'icudt_EFIGS.dat' }]
// after: ship full archive
resources.icu = [{ name:'icudt.dat' }]

// validate locale coverage before requesting display names
const supported = Intl.DisplayNames.supportedLocalesOf([localeName], { type: 'language' });
if (supported.length === 0) return; // ICU does not cover this locale

// SystemJS_GetLocaleInfo already wraps the throw in try/catch and forwards the string.
// On the managed side, inspect dstLength == -1 and fall back gracefully.

When it happens

Trigger: Requesting display names for a locale the loaded ICU archive does not cover (e.g. a CJK locale loaded with the EFIGS shard); invariant or minimal globalization data shipped; a locale whose region part is invalid and the fallback also returns undefined.

Common situations: Using sharded ICU data (icudt_EFIGS.dat) and requesting a locale outside that shard; enabling invariant mode but still querying display names; mismatched applicationCulture and shipped ICU archive.

Related errors

• Locale or culture name is null or empty. localeName=
• Failed to initialize ICU data
• Failed to load ICU data
• invariant globalization mode is inactive and no ICU data…
• Locale info for locale=

AI-assisted analysis of dotnet/runtime@60108ba66e (2026-08-10). Data as JSON: /api/errors/49c97b2c0e403d69. Report an issue: GitHub.

Appendix: source

Thrown at src/mono/browser/runtime/globalization-locale.ts:82

                        // handle non-standard or malformed locales by forwarding the locale code, e.g. "xx-u-xx"
                        stringToUTF16(dst, dst + 2 * localeNameOriginal.length, localeNameOriginal);
                        setI32(dstLength, localeNameOriginal.length);
                        return VoidPtrNull;
                    }
                    throw error;
                }
            } else {
                throw error;
            }
        }
        const localeInfo = {
            LanguageName: languageName,
            RegionName: regionName,
        };
        const result = Object.values(localeInfo).join(OUTER_SEPARATOR);

        if (!result)
            throw new Error(`Locale info for locale=${localeName} is null or empty.`);

        if (result.length > dstMaxLength)
            throw new Error(`Locale info for locale=${localeName} exceeds length of ${dstMaxLength}.`);

        stringToUTF16(dst, dst + 2 * result.length, result);
        setI32(dstLength, result.length);
        return VoidPtrNull;
    } catch (ex: any) {
        setI32(dstLength, -1);
        return stringToUTF16Ptr(ex.toString());
    }
}

View on GitHub (pinned to 60108ba66e)