"Failed to get data from the server"

I also got this... I just waited a few minutes and tried again and it worked. It had never happened before, and I had seen that was the message that appeared to spoofers in the last ban wave. I almost shat myself. Then I remembered "But wait, I am not a spoofer...". That calmed me down a bit.

This happens to me all the time when my network goes iffy. Sign out if it lets you, close the app, and restart. Usually works like a charm, but I had the same problem as you - wouldn't let me at all so I just gave up and went to bed. Had worked out by this AM.

Sounds like Community Day to me.

Pretty sure Niantic not receiving any data from their servers. Trading between 2 great friends...says it on both sides, but no stardust discount. Regular trade still 100 stardust, not the expected 80. Expect the worst cp range in play as a result.