Please make sure an objective is selected, and choose a creative type that matches the objective you've selected. (#1815159)

Why it happens

• Not every format works with every objective. For each objective, Meta publishes which formats (text, image, video, carousel, collection) are available on each placement; a format that is not available for the objective or for a selected placement does not go through.
• The objective is missing. The message also asks you to make sure an objective is selected at the campaign level.

How to fix it

1. In Ads Manager, open the campaign and check the objective selected at the campaign level.
2. Open the ad and, in Ad setup, choose a format listed as available for that objective in Meta’s “Available ad placements and ad formats by ad objectives” article.
3. If you need that exact creative, create a campaign with an objective that supports it.
4. Publish again.

What worked for other advertisers

In a long-running r/FacebookAds thread on this exact message, the reply that got thanked switches the ad set to manual placements:

1. Open the ad set, go to Placements and choose manual placements.
2. Untick Audience Network and Messenger.
3. Publish again.

6 replies confirm it worked (one says it did not), for example “Worked for me two years later dude! Thanks, you’re a life saver”. If the error stays, advertisers in the same thread report aligning the ad set’s performance goal with the campaign objective (for example landing page views instead of a conversion goal in a Traffic campaign).

Source: r/FacebookAds thread on #1815159

How to avoid it next time

• Choose the objective first, then build creatives in formats that the objective and your placements support.
• After changing a campaign’s objective or placements, re-open every ad and check its format.