Instagram error 100: Comment is invalid for a private reply

Subcode 2534025 rejects a private reply - the comment-to-DM feature - because the target comment cannot receive one. Meta documents private replies with hard rules: the reply must be sent "within 7 days from when the comment was created" for comments on posts, ads and reels; replies to Instagram Live comments "can only be sent during the live broadcast"; and "only one message can be sent" per comment. Break any of these - or target a comment that was deleted, or one authored by the account itself - and the comment is "invalid for a private reply."

This is a per-comment refusal, not a configuration problem. The same integration will succeed on a fresh comment while failing on an expired, deleted, or already-answered one. Comment-triggered DM automations mostly meet it in two forms: a backlog processor replying to comments older than 7 days, and a retry or duplicate event causing a second private reply to a comment that already consumed its single allowance.

Design comment automations as real-time consumers of the comments webhook rather than batch sweeps, so the 7-day and one-reply rules are naturally respected. Persist a sent-marker per comment ID with the same durability as the messages themselves. The private-reply rules and the rate ceilings that apply to them (750 per hour on posts and reels) are tabulated in the limits reference, and the window family's DM-side twin is 10/2534022.