Trying to run GPS Example. Compiles, loads ok, but comes up with a file not found error. Added External SD card. Newbie, missing something obvious (but not to me!). Using a Moto G5+. Android 27.
The GPS Example shows you the use of Runtimepermission.
If you want to write (or read) the external CD-Card then you need to do similar checks for them using runtimepermissions lib. See Runtimepermission-Tutorial: