Student or Learner
Do you have any objections to the meeting?
Do you have any objection to the meeting?
Standing alone as it does, this sentence is unclear. Is the meeting being planned and you want to know if I object to having the meeting? Is the meeting going on and do I object to something that is happening during the meeting? Is the meeting over and do I object to something that happened in the meeting? (I used do instead of did because most likely I would still object to whatever happened.) Are you asking only me or a group?
That aside, the most common form of this word in this usage, when asked of one person is objection. The asker wouldn't typically assume you might have more than one objection significant enough to make a list. If asking more than one person, then objections.
Before the meeting: Do you have any objection to a meeting? Does anyone object to a meeting?
During the meeting: Any objections? I used the plural form, assuming there are multiple attendees, and each might want to express their own objection(s).
After the meeting: Anything you objected to?