2.4.3.22. Error ERR_SPDY_PROTOCOL_ERROR

The issue may be observed in Chromium-based browsers (Chrome, Opera, Vivaldi, Brave, and others) operating on devices that use antivirus programs such as AVG or Avast, especially when using an SSL connection.

• If you are using any antivirus programs¹⁾, try disabling HTTPS scanning or adding the site where the error occurs to the exceptions. For example, to add a site to exceptions in Avast, perform the following:
  1. Go to the "Settings" section.
  2. Select "Active Protection".
  3. Open "Web Shield Protection".
  4. In the "Exceptions" section, add the sites where the error occurs.
  5. Check for errors.
• Try clearing the socket pool in Chrome:
  • In the browser's address bar, enter chrome://net-internals/#sockets.
  • Click "Flush socket pool":
  • Restart the browser and check for the error.
• Try to clear DNS cache.
• Try to clear your browser cache.