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Error Submitting Data: How to Fix ‘Failed to Fetch’?

Facing ‘Failed to Fetch’ when submitting form data to Google Sheets? Learn how to troubleshoot and resolve this common issue effectively.

byDev Solutions

April 5, 2025

Developer troubleshooting 'Failed to Fetch' error in console with debugging tips and coding books around.

⚠️ The "Failed to Fetch" error occurs when a JavaScript fetch() request fails to retrieve a response, often due to CORS restrictions or incorrect API configurations.
🔧 Deploying a Google Apps Script web app with the correct permissions can resolve authentication-related fetch failures.
🌐 Ensuring both the web page and API use HTTPS prevents mixed-content security blocks that can result in failed fetch requests.
🚀 Using properly structured JavaScript fetch requests with correct headers, HTTP methods, and JSON formatting helps prevent submission errors.
🛠️ Debugging network logs in browser developer tools helps identify specific reasons why a fetch request isn't working.

Error Submitting Data: How to Fix 'Failed to Fetch'?

When working with Google Sheets form submission, many developers encounter the "Failed to Fetch" error. This issue can be confusing, as it may stem from CORS restrictions, incorrect API configurations, or problems with network connectivity. Fortunately, understanding the root causes of the error and knowing how to fix it can help you get your web forms functioning correctly. This comprehensive guide will explain why the error occurs and provide step-by-step solutions to resolve it effectively.

Understanding the 'Failed to Fetch' Error

The "Failed to Fetch" error occurs when a JavaScript fetch() request fails to retrieve a response from the server. When submitting a web form to Google Sheets using Google Apps Script, this error usually points to one of the following:

A network issue preventing communication with the server.
Incorrect API permissions or setup in Google Apps Script.
Security policies like CORS blocking the request.

Since Google Sheets serves as an API backend for many web-based applications, ensuring proper API requests is critical to avoiding submission failures.

Common Causes of the 'Failed to Fetch' Error

1. CORS Policy Restrictions

Cross-Origin Resource Sharing (CORS) is a security policy enforced by web browsers to block unauthorized requests between different origins. If your web form is hosted on one domain (e.g., yourwebsite.com) but is sending a request to a Google Apps Script endpoint (e.g., script.google.com), the browser may block it.

Google Sheets API does not automatically handle CORS permissions, and requests from an untrusted source may be rejected.

How to Fix CORS Errors

Deploy Google Apps Script as a Public Web App – Set access to "Anyone, even anonymous".
Use JSONP or a third-party CORS proxy to bypass restrictions if necessary (not recommended for sensitive data).

2. Incorrect Google Apps Script Deployment Settings

If your Google Apps Script project is set to private or restricted to certain users, external form submissions may fail with a "Failed to Fetch" error.

Solution:

Go to your Google Apps Script editor.
Click Deploy > New Deployment.
Under "Select type," choose Web app.
In Who has access, select "Anyone" or "Anyone with the link".

This ensures that your script is publicly accessible for form submissions.

3. Mixed Content Issues (HTTP/HTTPS Mismatch)

Modern browsers block HTTP requests from secure (HTTPS) pages due to mixed-content security policies. If your website is secured (https://yourwebsite.com) but your Google Apps Script URL is non-secure (starting with http://), the request might be blocked.

Fix: Enforce HTTPS for All Requests

Ensure your Google Apps Script URL starts with https://.
If your website runs only on http://, upgrade to HTTPS using an SSL certificate.

4. Network Connectivity Problems

Some environments block requests to Google services due to:

Corporate firewalls blocking Google Scripts.
Poor internet connections leading to timeouts.

Troubleshooting Steps

Try form submission on a different network (using mobile data instead of Wi-Fi).
Disable browser extensions that might block outgoing requests.

5. Incorrect Fetch API Implementation

Errors in the JavaScript fetch request itself can cause the "Failed to Fetch" error. Issues may include:

Wrong HTTP method (Google Scripts expect POST, but you're sending GET).
Missing headers (such as "Content-Type": "application/json").

Correct Fetch Request Format

Make sure your fetch() request is structured like this:

fetch("https://script.google.com/macros/s/yourScriptID/exec", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
  },
  body: JSON.stringify({ name: "John Doe", email: "johndoe@example.com" }),
})
  .then(response => response.json())
  .then(data => console.log("Success:", data))
  .catch(error => console.error("Fetch Error:", error));

Ensuring correct syntax avoids common fetch errors.

Step-by-Step Troubleshooting Guide

If your fetch request is failing, follow these steps to diagnose and fix the issue:

1. Use Developer Tools to Inspect Errors

Open Chrome Developer Tools (F12 or Ctrl + Shift + I).
Go to the Console tab and check for error messages.
Switch to the Network Tab, refresh the page, and check failed requests.

2. Verify API Permissions

Check your Google Apps Script deployment settings (Who has access: Anyone).
Confirm that Internet users can access the script.

3. Test on a Different Network or Browser

If your script runs fine on a different network or device, the issue might be local firewall blocking.

4. Enable CORS if Necessary

Modify your Google Apps Script:

function doPost(e) {
  return ContentService.createTextOutput(
    JSON.stringify({ status: "success" })
  ).setMimeType(ContentService.MimeType.JSON);
}

This ensures your script sends a proper JSON response.

Preventing 'Failed to Fetch' Errors in the Future

To avoid getting stuck with similar issues in the future:

✔️ Test Google Apps Script permissions regularly and keep deployments updated.
✔️ Use tools like fetch() error handling to detect problems quickly.
✔️ Consider alternative backend solutions for scalability (e.g., Firebase).

By ensuring proper API implementations and debugging efficiently, you can fix 'Failed to Fetch' errors and enhance the reliability of your Google Sheets form submission process.