If you are also thinking why can't I attach files in gmail, then check this fixes to solve the Gmail attachment errors.

- You can Update the Flash Plug-in

- Get Grant Gmail permissions

- You can Update the Browser

- Open Gmail in Another Browser

- You can switch off Firewalls

- You can disable the Proxy Server

- You can try 3rd party alternatives

- Adjust the Network .http.spdy.enabled Setting in Firefox