I have registered connected application with partner's SalesForce on Partner API level. Connected app have defined following scopes (id, web, api and refresh_token).
When I try to invoke SOAP API over username, password and session id combination (this is not OAuth2.0 protocol/access token combination) in old fashion style I'm getting : INVALID_SESSION_ID: This session is not valid for use with the API
When partner turned off in SF App Access Settings, (Setup -> Manage Apps -> Connected Apps) following parameter : Limit access to apps that are currently installed and have "Admin approved users and pre-authorized" as their Permitted Users setting our application was in position to smoothly communicate with SF SOAP API.
What does this mean ? What I have to change in my configuration. I have asked here is it possible to call SOAP API without access token (in old fashion) if you have registered application as connected app. I got answer Yes.
I do not know what I am doing wrong.