That version of the SDK does use API v2, so it sounds like it is just users with an old version of your app.
One exception for the Java SDK in particular though is that it does still contain API v1 functionality (for now) to ease the migration. Just make sure you're not using DbxClientV1 anywhere in your latest code.
Thanks for your reply. It should be possible that some users use a old app version. I update my App to API v2 not long ago.
I use following SDK: "com.dropbox.core:dropbox-core-sdk:3.0.2". I hope that is the newest one.
I checked my latest code and i only use DbxClientV2. Now i'm sure i finished the migration to API v2.
Thank you