apify/crawlee · error · Error

Unsupported format: '${format}'. Use one of ${supportedForma

Error message

Unsupported format: '${format}'. Use one of ${supportedFormats.join(', ')}

What it means

When an explicit format is provided (or inferred from the path extension), BasicCrawler validates it against the list of supported formats (json, csv). If the format is not supported, this error is thrown naming the valid choices.

Source

Thrown at packages/basic-crawler/src/internals/basic-crawler.ts:2270

     * Retrieves all the data from the default crawler {@apilink Dataset} and exports them to the specified format.
     * Supported formats are currently 'json' and 'csv', and will be inferred from the `path` automatically.
     */
    async exportData<Data>(path: string, format?: 'json' | 'csv', options?: DatasetExportOptions): Promise<Data[]> {
        const supportedFormats = ['json', 'csv'];

        const formatMatch = /\.(json|csv)$/i.exec(path);
        if (!format && formatMatch) {
            format = formatMatch[1].toLowerCase() as 'json' | 'csv';
        }

        if (!format) {
            throw new Error(
                `Failed to infer format from the path: '${path}'. Supported formats: ${supportedFormats.join(', ')}`,
            );
        }

        if (!supportedFormats.includes(format)) {
            throw new Error(`Unsupported format: '${format}'. Use one of ${supportedFormats.join(', ')}`);
        }

        const dataset = await this.getDataset();
        const items = await dataset.export(options);

        if (format === 'csv') {
            let value: string;
            if (items.length === 0) {
                value = '';
            } else {
                const keys = options?.collectAllKeys
                    ? Array.from(new Set(items.flatMap(Object.keys)))
                    : Object.keys(items[0]);

                const { stringify } = await import('csv-stringify/sync');

                value = stringify([
                    keys,

View on GitHub (pinned to dbe57fb09c)

Solutions

1. Use 'json' or 'csv' as the format value
2. If you need another format, export as JSON and convert afterwards with your own code
3. Check the casing of the format string (it must match the supported list, e.g. lowercase 'csv')

Example fix

// before
await crawler.exportTo('data.xml', { format: 'xml' });
// after
await crawler.exportTo('data.json', { format: 'json' });

const SUPPORTED = ['json','csv'];
if (format && !SUPPORTED.includes(format.toLowerCase())) throw new Error(`Unsupported format ${format}; use json or csv`);

try { await crawler.exportTo(p, { format }); } catch (e) { if (String(e.message).startsWith('Unsupported format')) { /* retry with 'json' */ } else throw e; }

When it happens

Trigger: Passing a format option such as 'xml', 'xlsx', 'ndjson', or 'JSONL' to the dataset export call, or an explicit format that doesn't match 'json' or 'csv'.

Common situations: Users assuming Excel/NDJSON export is supported; passing uppercase 'JSON' while supportedFormats comparison is case-sensitive; copying options from other data libraries.

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AI-assisted analysis of apify/crawlee@dbe57fb09c (2026-08-30). Data as JSON: /api/errors/f2b675a8231b4540. Report an issue: GitHub.