Minecraft new launcher problem
This error can happen if compatibility mode is turned on for the launcher. Check the options on the launcher shortcut and make sure that box isn't ticked. To do this, right click on the launcher shortcut and select properties. Navigate to the Compatibility tab and then uncheck the
Run this program in compatibilty mode for:
box.
If you are still having problems, you can download the old launcher at https://minecraft.net/en-us/download/alternative. Be sure to click on the second download link if you're on Windows or the third link for Macs.
Hope this helps!