Some Android users are unable to log-in to Dragalia Lost after updating the mobile game to version 1.6.0. However, you can rest assured that the development team is aware of the issue and is working on getting a fix out as soon as it becomes available. Read on below for the official announcement regarding this:
Regarding a Log-In Issue with Some Android Devices
We have confirmed that some Android devices are unable to log-in to the game after updating it to version 1.6.0. We are currently investigating this issue. Any further updates will be added to this notice. Thank you for playing Dragalia Lost.