Hello Donat,
Thank you for that information. After investigating we were able to identify the problem.
It appears that we have a bug that is preventing the app from showing an error if the election has no voters or has invalid or duplicate voter emails. We are currently working on a fix.
In the meantime, you can go to the "Voters" tab of your election to make sure you have voters and you do not have any invalid or duplicate emails. If you have duplicate emails, you can use the "Clean emails" button to eliminate the duplicates. After that, you should be able to start your election.
Please let us know if you have any other issues.
Sincerely,
— Damien