Expected value of header '{value}' to be String, but '{value}' is found.

Error

Expected value of header "${key}" to be String, but "${typeof value}" is found.

What it means

Puppeteer raised this from its WebDriver BiDi code. In practice, it usually means your script reached a browser, page, frame, element, or option state that the API cannot use safely.

How to fix it

• This API is not available through the WebDriver BiDi connection yet.
• Use the default CDP connection for this feature, or remove the unsupported option when launching/connecting with BiDi.

Minimal guard

try {
  // Run the Puppeteer operation that triggers this error.
} catch (error) {
  if (error instanceof Error && error.message.includes("Expected value of header \"")) {
    // Apply the fix above, then retry or fail with a clearer message.
  }
  throw error;
}