I have a Spark that I've flown before on the same Samsung Galaxy S9 running android version 9 , but now the app crashes everytime I launch it.  It links up to the wifi. I luanch the ap. and it says go fly. I push go fly, it goes to the mains creen for a second, then crashes. I get a message "DJI Go4 keeps stopping"

Hi Danswack, my apologies for all the trouble. I would recommend  you back up your files and then sync your flight records and then reinstall  app. May  I know if this happen when you're using a different mobile device? Please provide a short video of the issue for further checking. You can upload it by using google-drive or Dropbox and provide the link here. Thank you.