I have been having the pop up in the tile plague me for a couple days now. I have had the game since 2010 and just migrated my account a couple days ago. At first, I was logged into the launcher but it said "No connection". I then logged out but couldn't log back in. I hit the "Continue without login >" button, then logged in on the next screen and I was connected. That worked a couple times and was able to connect to servers and play with friends, but now will no longer work.
I have tried numerous things.
-running as administrator
-disabling firewall completely and trying again
-turned off all antivirus/uninstalled incompatible antivirus
-installed on my laptop which has never had minecraft installed, and ran into the same issue (so I think it is account related)
It is not an internet problem this is the only app that "can't connect to the internet"