What causes "Invalid language" in DIYgod/RSSHub?

Use one of the documented two-letter language codes: en, de, es, fi, fr, it, ja, nl, no, pl, pt, ru, sv, zh (or omit for en).

DIYgod/RSSHub · warning · InvalidParameterError

Invalid language

Error message

Invalid language

What it means

Thrown by the MyFigureCollection activity route when the :language path parameter is non-empty and fails the isValidHost regex check (a single-label hostname pattern: starts alphanumeric, contains only alphanumeric/hyphen, max 63 chars). The language is used as a subdomain prefix (e.g. {language}.myfigurecollection.net), so it must be a valid DNS label.

Source

Thrown at lib/routes/myfigurecollection/activity.tsx:76

| nl | Nederlands |
| no | Norsk      |
| pl | Polski     |
| pt | Português  |
| ru | Русский    |
| sv | Svenska    |
| zh | 中文       |`,
};

async function handler(ctx) {
    const category = ctx.req.param('category') ?? '-1';
    const language = ctx.req.param('language') ?? '';
    const latestAdditions = ctx.req.param('latestAdditions') ?? '1';
    const latestEdits = ctx.req.param('latestEdits') ?? '1';
    const latestAlerts = ctx.req.param('latestAlerts') ?? '1';
    const latestPictures = ctx.req.param('latestPictures') ?? '1';

    if (language && !isValidHost(language)) {
        throw new InvalidParameterError('Invalid language');
    }

    const rootUrl = `https://${language === 'en' || language === '' ? '' : `${language}.`}myfigurecollection.net`;
    const currentUrl = `${rootUrl}/browse.v4.php?mode=activity&latestAdditions=${latestAdditions}&latestEdits=${latestEdits}&latestAlerts=${latestAlerts}&latestPictures=${latestPictures}&rootId=${category}`;

    const response = await got({
        method: 'get',
        url: currentUrl,
    });

    const $ = load(response.data);

    const items = $('.activity-wrapper')
        .toArray()
        .map((item) => {
            const $item = $(item);

            return {

View on GitHub (pinned to bed535e087)

Solutions

Use one of the documented two-letter language codes: en, de, es, fi, fr, it, ja, nl, no, pl, pt, ru, sv, zh (or omit for en).
Avoid dots, underscores, spaces, or non-ASCII characters in the language segment.
List valid codes in the error message for discoverability.

Example fix

// before
if (language && !isValidHost(language)) {
    throw new InvalidParameterError('Invalid language');
}

// after — explicit allowlist with helpful message
const allowedLangs = ['', 'en', 'de', 'es', 'fi', 'fr', 'it', 'ja', 'nl', 'no', 'pl', 'pt', 'ru', 'sv', 'zh'];
if (language && !allowedLangs.includes(language.toLowerCase())) {
    throw new InvalidParameterError(`Invalid language '${language}'. Supported: ${allowedLangs.filter(Boolean).join(', ')}`);
}

Defensive patterns

Strategy: validation

Validate before calling

const MFC_LANGUAGES = ['', 'en', 'de', 'es', 'fi', 'fr', 'it', 'ja', 'nl', 'no', 'pl', 'pt', 'ru', 'sv', 'zh'];
const language = (ctx.req.param('language') ?? '').toLowerCase();
if (language && !MFC_LANGUAGES.includes(language)) {
    throw new InvalidParameterError(`Invalid language '${language}'. Supported: ${MFC_LANGUAGES.filter(Boolean).join(', ')}`);
}

Type guard

const MFC_LANGS = new Set(['', 'en', 'de', 'es', 'fi', 'fr', 'it', 'ja', 'nl', 'no', 'pl', 'pt', 'ru', 'sv', 'zh']);
function isMfcLanguage(l: string): boolean {
    return MFC_LANGS.has(l.toLowerCase());
}

Prevention

Use an explicit allowlist of valid language codes instead of the generic hostname regex.
Share the allowlist between this route and the sibling index route.
Normalize case before validation.
Include the supported list in the error message.

When it happens

Trigger: Passing a language code with invalid hostname characters: dots (e.g. 'zh-CN'), underscores, spaces, or special chars. Passing a value longer than 63 characters. Passing an empty-but-truthy value like a single space. Valid codes (en, de, es, fr, ja, zh, etc.) pass because they are clean DNS labels.

Common situations: User passes 'zh-CN' (with hyphen-region) thinking it is an IETF tag — the hyphen makes it 'zh' label + invalid second label conceptually, but actually the regex allows hyphens so 'zh-CN' would pass; the real failure is codes with dots, underscores, or non-ASCII. User passes a full hostname like 'en.myfigurecollection.net'. User passes uppercase which actually passes (regex is case-insensitive).

Related errors

AI-assisted analysis of DIYgod/RSSHub@bed535e087 (2026-08-12). Data as JSON: /api/errors/9f578c3c5c3356bb. Report an issue: GitHub.