Found probably the only solution on the entire internet.
For Windows:
Run the Notepad program as administrator.
Click the "File" button in the upper left corner, then click the "Open" button.
In the bottom text box, paste C:\Windows\System32\Drivers\etc\hosts.
Find and delete all lines related to Minecraft / Mojang.
Save the file and restart the mojang launcher.
for Mac
Open Terminal.
Enter the command sudo nano /private/etc/hosts
Enter the password for your account.
None of the above helped. I've seen somewhere that a guy was helped by reinstalling windows, but I think that's too radical a solution.
Kuragane
Found probably the only solution on the entire internet.
For Windows:
Run the Notepad program as administrator.
Click the "File" button in the upper left corner, then click the "Open" button.
In the bottom text box, paste C:\Windows\System32\Drivers\etc\hosts.
Find and delete all lines related to Minecraft / Mojang.
Save the file and restart the mojang launcher.
for Mac
Open Terminal.
Enter the command sudo nano /private/etc/hosts
Enter the password for your account.
Find and delete all lines related to Minecraft / Mojang.
Save the file and restart the mojang launcher.