If you don't see OneDrive among the locations, there are two possibilities:
...button in the file selection dialog, then
Edit, and make sure that OneDrive is turned on.
“Failed to open file. Reason: The requested operation couldn't be completed because the feature is not supported." This error message might appear if your network connection is unstable or restricted by a firewall. Switching to another network should resolve the issue.
If synchronization stopped working after you have upgraded to iOS 13, remove your database from KeePassium, reinstall the OneDrive app, then add the database again.
If you encounter any other issues with OneDrive, please let us know.
Last Updated: 2019-10-13