wp-content/plugins/wordpress-social-login/hybridauth/Hybrid/Providers/Odnoklassniki.php
line 145 (function getUserProfile())
insert this
$key_temp = ($this->config['keys']['key']) ? $this->config['keys']['key'] : 'PUBLIC KEY';
and change
$sig = md5('application_key=' . $key_temp . 'method=users.getCurrentUser' . md5($this->api->access_token . $this->api->client_secret));
$response = $this->api->api( '?application_key=' . $key_temp . '&method=users.getCurrentUser&sig=' .$sig);
I made these changes and it worked.
there is no field with public key in settings for ‘odnoklasniki.ru’