GitHub GraphQL addPullRequestReviewThreadReply returned no…

Error message

GitHub GraphQL addPullRequestReviewThreadReply returned no comment

What it means

Thrown by `add_pull_request_review_thread_reply` after the `addPullRequestReviewThreadReply` GraphQL mutation returns no comment in its payload. The reply was not created (or its payload was stripped), so the client cannot convert it to a `PullRequestComment` and bails.

Solutions

Check the GraphQL `errors` array in the response for the real cause (invalid thread id vs permission).
Re-list the review threads (`list_review_threads`) to obtain fresh thread node ids before replying.
Confirm the token has write access to create review comments in the repo.
If the thread was resolved/deleted, post a regular PR comment instead of a thread reply.
Retry once after refreshing the thread id if the failure was transient.

Example fix

// before
let reply = client.add_pull_request_review_thread_reply(&stale_thread_id, "done").await?;
// after
let threads = client.list_pull_request_review_threads(owner, repo, pr_number).await?;
if let Some(t) = threads.iter().find(|t| t.id == thread_id) {
    let reply = client.add_pull_request_review_thread_reply(&t.node_id, "done").await?;
}

Defensive patterns

Strategy: validation

Validate before calling

let threads = client.list_pull_request_review_threads(owner, repo, pr).await?;
if !threads.iter().any(|t| t.node_id == thread_id) {
    return Err(anyhow!("thread {thread_id} no longer exists on {owner}/{repo}#{pr}"));
}
if reply.trim().is_empty() { return Err(anyhow!("reply must not be empty")); }

Type guard

fn thread_is_open(t: &PullRequestReviewThread) -> bool { !t.is_resolved && !t.is_outdated }

Try / catch

match client.add_pull_request_review_thread_reply(&thread_node_id, reply).await {
    Ok(c) => c,
    Err(e) if e.to_string().contains("no comment") => {
        // fall back to a regular PR comment
        client.create_pull_request_comment(owner, repo, pr, reply).await?.into()
    }
    Err(e) => return Err(e),
}

Prevention

Re-list threads before replying; ids go stale after force-pushes.
Fall back to a top-level PR comment when the thread is gone or resolved.
Ensure the token can create review comments (write access).
Skip replying to threads marked outdated instead of failing.

When it happens

Trigger: Replying to a review thread using an invalid/stale thread node id; the thread was resolved or deleted before the reply; GraphQL-level errors (permission denied on the repository, bad node id) yielding a null `comment`; the thread's PR was force-pushed and threads were regenerated.

Common situations: Caching thread ids from an earlier review session after the PR was rebased; replying on a private repo with a read-only token; two clients replying concurrently with one deleting the thread; GitHub UI removed outdated threads after new commits.

Understand the failure class

Background: "invalid response format", "malformed payload", "missing data field": when an API returns 200 but the response shape is wrong — this error's family across 23 libraries.

Related errors

AI-assisted analysis of gitbutlerapp/gitbutler@58e5313667 (2026-09-18). Data as JSON: /api/errors/4639696faa4d30fd. Report an issue: GitHub.

Appendix: source

Thrown at crates/but-github/src/client.rs:1268

        #[serde(rename_all = "camelCase")]
        struct QueryData {
            add_pull_request_review_thread_reply: Option<ReplyPayload>,
        }

        #[derive(Deserialize)]
        struct ReplyPayload {
            comment: Option<GraphQlReviewThreadComment>,
        }

        let data: QueryData = self
            .graphql_query(GQL_ADD_REVIEW_THREAD_REPLY, &Variables { thread_id, body })
            .await?;

        let Some(comment) = data
            .add_pull_request_review_thread_reply
            .and_then(|payload| payload.comment)
        else {
            bail!("GitHub GraphQL addPullRequestReviewThreadReply returned no comment");
        };

        Ok(comment.into())
    }

    /// List the diff-anchored review threads on a pull request, oldest
    /// first.
    ///
    /// GraphQL rather than REST: `/pulls/{n}/comments` reports neither the
    /// thread a comment belongs to nor whether that thread was resolved,
    /// and a resolved thread must not read as still waiting on a reply.
    pub async fn list_pull_request_review_threads(
        &self,
        owner: &str,
        repo: &str,
        pr_number: i64,
    ) -> Result<Vec<PullRequestReviewThread>> {
        #[derive(Serialize)]

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