dotnet/runtime · error · Error

Locale info for locale=

Error message

Locale info for locale=${localeName} exceeds length of ${dstMaxLength}.

What it means

Thrown by SystemJS_GetLocaleInfo in globalization-locale.ts when the resolved locale info string (LanguageName##RegionName) is longer than dstMaxLength, the managed-side destination buffer capacity. The check protects against buffer overflow when marshalling the result back to managed memory. Caught locally, reported to managed code via dstLength=-1 and the error string.

Solutions

Increase the destination buffer size (dstMaxLength) on the managed side that calls the interop.
Update the .NET runtime to a version whose managed caller allocates a correctly sized buffer.
If using a custom interop wrapper, size the buffer from the locale string length plus headroom.

Example fix

// before: fixed 64-char buffer
var buf = new string('\0', 64);
// after: size generously for display names
var buf = new string('\0', 512);

Defensive patterns

Strategy: validation

Validate before calling

// managed side: allocate a buffer large enough for localized names
const int MaxLocaleInfoLength = 512;
var dst = new string('\0', MaxLocaleInfoLength);

Try / catch

// forwarded via dstLength=-1; caller checks that and resizes/retries
if (dstLength == -1) { /* increase buffer, retry once */ }

Prevention

Size locale-info buffers generously (>= 256 chars).
Keep the runtime and its managed caller from the same build so buffer sizing stays consistent.
Treat dstLength=-1 as a recoverable signal and fall back to the raw locale code.

When it happens

Trigger: Managed code allocated a destination buffer too small for the localized display names; very long language/region display names (some locales produce multi-word names); a downstream change that increased display-name length without resizing the native buffer.

Common situations: A runtime/SDK update that changed ICU display-name formatting so results grew; a custom marshaler with a hardcoded buffer size; locales with long names (e.g. some zh-Hant names) against a too-small buffer.

Related errors

AI-assisted analysis of dotnet/runtime@60108ba66e (2026-08-10). Data as JSON: /api/errors/df82cb13a72ce7ae. Report an issue: GitHub.

Appendix: source

Thrown at src/mono/browser/runtime/globalization-locale.ts:85

                        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)