Recently I got a new smartphone, and I wanted to move all my flashcards (there's a lot of them) from the first phone to the second one. However, whenever I try to export them as XML file I get a message saying "The export did not complete succesfully". And when I picked Backup Database, the message I saw said "Sorry, your flashcards could not be backed up". How can I fix it and practice flashcards on my new phone?