My form will not publish

• The form has no questions. A welcome screen on its own is not publishable.
• A logic rule points at a question that has been deleted. Open the Logic tab; the broken rule is flagged, and deleting or repointing it clears the block.
• You are in support view. If the dark banner is across the top of the screen, somebody is viewing your account read-only and every change is refused. Close the banner to leave it.

#Still stuck

Check the publish modal itself. It lists what is missing above the confirm button rather than failing silently.