What causes "Session file not found: {}" in nikivdev/code?

Verify the session ID is correct and the .jsonl file exists under the Claude projects directory.

Session file not found: {}

Error message

Session file not found: {}

What it means

This error is thrown when constructing a Claude session file path (`<claude projects dir>/<project_folder>/<session_id>.jsonl`) for a checkpoint/rollback operation and the file does not exist on disk. The library bails before reading exchanges because there is no session history to rewind.

Source

Thrown at src/ai.rs:1740

        return Ok((context.trim().to_string(), last_ts));
    }

    let path_str = project_path.to_string_lossy().to_string();
    let project_folder = path_to_project_name(&path_str);

    let projects_dir = match provider {
        Provider::Claude | Provider::All => get_claude_projects_dir(),
        Provider::Codex => get_codex_projects_dir(),
        Provider::Cursor => get_cursor_projects_dir(),
    };

    let session_file = projects_dir
        .join(&project_folder)
        .join(format!("{}.jsonl", session_id));

    if !session_file.exists() {
        bail!("Session file not found: {}", session_file.display());
    }

    // Collect exchanges after the checkpoint timestamp
    let mut exchanges: Vec<(String, String, String)> = Vec::new(); // (user_msg, assistant_msg, timestamp)
    let mut current_user: Option<String> = None;
    let mut current_ts: Option<String> = None;
    let mut last_ts: Option<String> = None;

    for_each_nonempty_jsonl_line(&session_file, |line| {
        if let Ok(entry) = crate::json_parse::parse_json_line::<JsonlEntry>(line) {
            let entry_ts = entry.timestamp.clone();

            // Skip entries before checkpoint
            if let (Some(since), Some(ts)) = (since_ts, &entry_ts) {
                if ts.as_str() <= since {
                    return;
                }
            }

View on GitHub (pinned to a747e741ae)

Solutions

Verify the session ID is correct and the .jsonl file exists under the Claude projects directory.
Recompute the project folder from the correct working directory (path_to_project_name depends on it).
List available sessions in ~/.config (or equivalent) claude projects dir to find the right ID.
Re-create the session if the file was pruned; checkpoints for it are unrecoverable.

Example fix

// before
f restore --session abc123   // typo
// after
ls ~/.claude/projects/<project-folder>/  # confirm abc124.jsonl exists
f restore --session abc124

Defensive patterns

Strategy: validation

Validate before calling

// shell
SESSION_FILE="$HOME/.claude/projects/$(pwd | sed 's|/|-|g')/$SESSION_ID.jsonl"
[ -f "$SESSION_FILE" ] || { echo "missing: $SESSION_FILE"; exit 1; }

Type guard

fn session_file_exists(projects_dir: &Path, project_folder: &str, session_id: &str) -> bool {
    projects_dir.join(project_folder).join(format!("{}.jsonl", session_id)).exists()
}

Try / catch

// rust
match restore_checkpoint(...) {
    Err(e) if e.to_string().starts_with("Session file not found") => {
        eprintln!("Verify the session ID and project directory: {e}");
    }
    Err(e) => return Err(e),
    Ok(v) => v,
}

Prevention

List existing .jsonl session files before referencing a session ID.
Run restore/summary commands from the original project directory.
Back up session files before Claude prunes old ones.

When it happens

Trigger: Calling the checkpoint-restore path with a session_id whose `<projects-dir>/<project-folder>/<session_id>.jsonl` file is missing — e.g. a deleted, pruned, or mistyped session ID, or a project folder name mismatch.

Common situations: Restoring an old checkpoint after Claude cleaned up old sessions; typos in the session ID; running from a different working directory so the project folder resolves differently.

Related errors

AI-assisted analysis of nikivdev/code@a747e741ae (2026-09-01). Data as JSON: /api/errors/098323d68ee997e3. Report an issue: GitHub.