Things to try:
1. Another browser (for Windows Internet Explorer, Edge - if you have Windows 10 -, Firefox and Chrome are free).
2. Use a service like wetransfer.com (free up to 2 GB)
3. An e-mail program like Thunderbird, linked to your gmail-account
4. Put those files in the cloud (like in your Dropbox folder, in Google Docs or in Onedrive) and send a link to the recipients.
Hello! As I stated on my subject, I have a couple of documents to send. But when I try to upload the files on gmail and Messenger, my laptop says "Upload failed. Make sure you're uploading a valid file." I tried restarting my device but still can't. Anyone know how to solve this issue? Thank you!