"Invalid user id" - can't login to new publisher accounts

2016-07-22 12:26:44 [0.001051] [] [2065746882] [24] [API] [KalturaStatement->execute] DEBUG: Sql took - 0.00054216384887695 seconds
2016-07-22 12:26:44 [0.001520] [] [2065746882] [25] [API] [KalturaFrontController->getExceptionObject] ERR: exception ‘KalturaAPIException’ with message ‘Invalid user id’ in /opt/kaltura/app/plugins/admin_console/system_partner/services/SystemPartnerService.php:209
Stack trace:
#0 [internal function]: SystemPartnerService->getAdminSessionAction(112, ‘dev.fr…’)

In the admin console, whenever I try to go from Publishers -> Actions -> Manage OR Publishers -> Actions -> KMC Users -> Login, I get the preceding error. And I reach a page like this:

Any ideas why? Makes it very annoying to set up new publishers

My primary suspicion is that in /opt/kaltura/app/configurations/admin.ini
settings.serviceUrl = "JUSTHOST_NAME"
When in fact, it should be:
settings.serviceUrl = "http://JUSTHOST_NAME"
settings.serviceUrl = “https://JUSTHOST_NAME”