I have imported the client config file to official OpenVPN client for Android.
The config file contains CA cert but no client cert or key. That's fine because i have
auth-user-pass directive in it.
But when I try to connect, a window pops up saying:
This profile doesn't include a client certificate. Continue connecting without a certificate or select one from the Android keychain?
If I choose to continue, it connects but this window appears every time I want to connect.
The same profile works fine on Windows (official OpenVPN GUI) and VPN Client Pro (unofficial client from Play Store).
Why it is looking for client certificate when the authentication method is user+pass?
EDIT for JW0914:
Since you are providing wrong information I did a little bit of search and found the answer:
As it is described here the key is to add "--verify-client-cert none" to the server config file.