Warning: the visa agent in Lisbon said one thing to me that I still repeat to every new nomad
I was renewing my D7 visa at the AIMA office in Lisbon two weeks ago and the agent, a lady named Sofia, looked at my folder and asked if I had my NIF printout plus the receipt from the last payment. She said most people show up with the paper copy and get sent home, so keep both on your phone and a backup in email. I asked her how often that happens and she said "every single morning." Now I keep a digital folder with every doc scanned and dated. What's in your backup folder that actually saved you at a border or office?