A Unity ID allows you to buy and/or subscribe to Unity products and services, shop in the Asset Store and participate in the Unity community.
Separate names with a comma.
remove unity and install again.. it solve me..
check android plugin if missing then install it other wise override on it. hope it's help full.
1> check Edit > Prefrence 2> Goto Windows>PackageManager install Visual Studio Editor Now Open Scipt. this problem is in 2019.3 alpha