What is the configuration for an paid event that has no online payment option?
I have a Drupal/CiviCRM website running since quite some time for courses I provide. People register online, and only when there are enough people the course takes place. I then send people an invoice (per mail) that they have to pay.
I'm now stuck with a bug where I receive a "SQLSTATE: Integrity constraint violation: 1048 Column 'tid' cannot be null" error message, which I have the impression is linked to an error in my event configuration.