windmill-labs/windmill · error

An error occurred when generating CSV:

Error message

An error occurred when generating CSV:

What it means

convertJsonToCsv wraps the json-2-csv `Parser.parse` call and rethrows any parsing failure with this prefix. It is thrown when the input array cannot be serialized to CSV — typically malformed row objects, values the parser cannot handle, or a non-array input.

Source

Thrown at frontend/src/lib/components/table/tableUtils.ts:56

			})
			return {
				_id: nextId++,
				rowData
			}
		})
		return [hds, objs]
	} else {
		return [[], []]
	}
}

export function convertJsonToCsv(arr: Array<Record<string, any>>): string {
	try {
		const parser = new Parser({})
		const csv = parser.parse(arr)
		return csv
	} catch (err) {
		throw new Error('An error occurred when generating CSV:' + err)
	}
}

View on GitHub (pinned to e474e8803c)

Solutions

1. Log the caught `err` (it is appended to the message) to see the exact parser complaint.
2. Sanitize/flatten rows before parsing: map values to primitives or strings (JSON.stringify nested objects).
3. Ensure the input is a non-empty array of plain objects with consistent keys.
4. Upgrade or pin the json-2-csv dependency if the failure is a known parser bug.

Example fix

// before
const csv = convertJsonToCsv(rawRows) // may throw
// after
const rows = rawRows.map((r) =>
  Object.fromEntries(Object.entries(r).map(([k, v]) => [k, typeof v === 'object' ? JSON.stringify(v) : v]))
)
const csv = convertJsonToCsv(rows)

function isCsvSafe(rows: unknown): rows is Array<Record<string, unknown>> {
  return Array.isArray(rows) && rows.length > 0 &&
    rows.every((r) => r !== null && typeof r === 'object' && !Array.isArray(r))
}

function isRecordArray(v: unknown): v is Array<Record<string, any>> {
  return Array.isArray(v) && v.every((x) => typeof x === 'object' && x !== null && !Array.isArray(x))
}

try {
  const csv = convertJsonToCsv(rows)
} catch (e) {
  toast.error('CSV export failed: ' + (e as Error).message)
  // fall back to JSON download
  downloadJson(rows)
}

When it happens

Trigger: Calling convertJsonToCsv(arr) where `arr` contains data the json-2-csv Parser cannot serialize (nested/circular structures it chokes on, invalid delimiters via the default config, or `arr` not being an array of records).

Common situations: Exporting table data to CSV from the result grid with unusual cell values (objects, Dates in odd shapes, nulls in key positions); passing undefined/empty or heterogeneous rows from an API response.

Related errors

• CSV S3 input requires the `parquet` feature to be enabled on
• Could not generate OpenAPI document in YAML format: {}
• Could not generate OpenAPI document in JSON format: {}
• invalid json-float
• row over budget

AI-assisted analysis of windmill-labs/windmill@e474e8803c (2026-09-03). Data as JSON: /api/errors/db5be72516b8e641. Report an issue: GitHub.