wavetermdev/waveterm · error

Invalid data URL

Error message

Invalid data URL

What it means

parseDataUrl parses data: URLs into a mime type and byte buffer. It strictly requires the string to begin with the "data:" scheme; anything else is rejected with this error because it cannot be interpreted as a data URL.

Source

Thrown at frontend/util/util.ts:452

                return "\\f";
        }
        if (code === 0x1b) return "\\x1b"; // escape
        if (code < 0x20 || code === 0x7f) return `\\x${code.toString(16).padStart(2, "0")}`;
        return ch;
    });
}

function cn(...inputs: ClassValue[]) {
    return twMerge(clsx(inputs));
}

type ParsedDataUrl = {
    mimeType: string;
    buffer: Uint8Array;
};

function parseDataUrl(dataUrl: string): ParsedDataUrl {
    if (!dataUrl.startsWith("data:")) throw new Error("Invalid data URL");
    const [header, data] = dataUrl.split(",", 2);
    if (data === undefined) throw new Error("Invalid data URL: missing data");

    const meta = header.slice(5);
    let mimeType = "text/plain;charset=US-ASCII";
    const parts = meta.split(";");
    if (parts[0]) mimeType = parts[0];
    const isBase64 = parts.some((p) => p.toLowerCase() === "base64");

    let buffer: Uint8Array;
    if (isBase64) {
        buffer = base64ToArray(data);
    } else {
        // assume text
        const decoded = decodeURIComponent(data);
        buffer = new TextEncoder().encode(decoded);
    }

View on GitHub (pinned to a4447c1563)

Solutions

1. Inspect the input string; confirm it starts with "data:".
2. If you only have raw base64, wrap it: `data:${mimeType};base64,${raw}`.
3. Skip the call for non-data URLs (check startsWith) and handle them through a different path.
4. Verify the source of the string (upload, clipboard, config) is producing a full data URL.

Example fix

// before
const parsedUrl = parsed(imageSrc); // imageSrc = "iVBORw0KGgo..."
// after
const dataUrl = imageSrc.startsWith("data:") ? imageSrc : `data:image/png;base64,${imageSrc}`;
const parsedUrl = parsed(dataUrl);

if (typeof input === "string" && input.startsWith("data:")) {
  const result = parsed(input);
} else {
  // treat as regular URL or raw base64, route accordingly
}

function isDataUrl(s: unknown): s is string {
  return typeof s === "string" && s.startsWith("data:");
}

try {
  return parsed(dataUrl);
} catch (e) {
  if (String(e.message).startsWith("Invalid data URL")) {
    console.warn("not a data URL:", dataUrl.slice(0, 32));
    return null;
  }
  throw e;
}

When it happens

Trigger: Calling parseDataUrl (via the parsed helper) with a plain http(s) URL, a bare base64 string, an empty string, or a data URL that lost its scheme after trimming/splitting.

Common situations: Storing only the base64 payload in a config and forgetting the "data:" prefix, copying an <img src> that was a normal URL, or string processing that stripped the prefix.

Related errors

• Invalid data URL: missing data
• invalid data URL: must start with 'data:'
• tabid and blockid are required
• Block not found: ${blockId}
• Block not found in tab: ${blockId}

AI-assisted analysis of wavetermdev/waveterm@a4447c1563 (2026-09-01). Data as JSON: /api/errors/76c6d1313daaea82. Report an issue: GitHub.