If you can't submit your study because of a session times error, your calendar slots are breaking one of three rules. Check these in order.
Slots in the past. Remove any session time that has already passed.
Not enough slots. You need more session times than participants. If your quota is 10, offer comfortably more than 10 slots so participants have real choice and you have buffer for reschedules.
Slots starting too soon. Sessions today (or before your study could finish review) can't be offered to participants. Start your sessions at least a day out.
Fix the flagged slots, and the error clears so you can submit.
Still stuck?
The submit step typically points at what's failing. The Review & Submit page should have some clues.
If the error persists after checking all three causes, message us on live chat with your study link and a screenshot and we'll take a look.