zellij-org/zellij · error · anyhow::Error

failed to find pane with id {pane_id:?}

Error message

failed to find pane with id {pane_id:?}

What it means

Returned by Tab::write_to_pane_id when the target pane id is absent from all three registries searched: floating panes, tiled panes, and the suppressed-panes map. The write to that specific pane is aborted; this usually means the pane was closed between the moment the caller resolved its id and the moment the write executed.

Source

Thrown at zellij-server/src/tab/mod.rs:4405

        key_with_modifier: &Option<KeyWithModifier>,
        raw_input_bytes: Vec<u8>,
        raw_input_bytes_are_kitty: bool,
        pane_id: PaneId,
        client_id: Option<ClientId>,
        completion_tx: Option<NotificationEnd>,
    ) -> Result<bool> {
        // returns true if we need to update the UI (eg. when a command pane is closed with ctrl-c)
        let err_context = || format!("failed to write to pane with id {pane_id:?}");

        let mut should_update_ui = false;
        let is_sync_panes_active = self.is_sync_panes_active();

        let active_pane = self
            .floating_panes
            .get_mut(&pane_id)
            .or_else(|| self.tiled_panes.get_pane_mut(pane_id))
            .or_else(|| self.suppressed_panes.get_mut(&pane_id).map(|p| &mut p.1))
            .ok_or_else(|| anyhow!(format!("failed to find pane with id {pane_id:?}")))
            .with_context(err_context)?;

        // We always write for non-synced terminals.
        // However if the terminal is part of a tab-sync, we need to
        // check if the terminal should receive input or not (depending on its
        // 'exclude_from_sync' configuration).
        let should_not_write_to_terminal = is_sync_panes_active && active_pane.exclude_from_sync();

        if should_not_write_to_terminal {
            return Ok(should_update_ui);
        }

        match pane_id {
            PaneId::Terminal(active_terminal_id) => {
                match active_pane.adjust_input_to_terminal(
                    key_with_modifier,
                    raw_input_bytes,
                    raw_input_bytes_are_kitty,

View on GitHub (pinned to 98a0837077)

Solutions

  1. Re-resolve the pane id from live state immediately before writing instead of caching it
  2. If using sync-panes, expect and tolerate per-pane write failures when some synced panes exit; reopen panes as needed
  3. For queued/async actions, validate the id with tab.get_pane_with_id (or equivalent) right before dispatch
  4. Upgrade zellij - races between input routing and pane exit have seen fixes; check CHANGELOG.md

Example fix

// before
let active_pane = self.floating_panes.get_mut(&pane_id)
    .or_else(|| self.tiled_panes.get_pane_mut(pane_id))
    .or_else(|| self.suppressed_panes.get_mut(&pane_id).map(|p| &mut p.1))
    .ok_or_else(|| anyhow!(format!("failed to find pane with id {pane_id:?}")))
    .with_context(err_context)?;

// caller-side: validate before dispatching queued input
if tab.get_pane_with_id(pane_id).is_none() {
    log::debug!("dropping write to dead pane {pane_id:?}");
    return Ok(should_update_ui);
}
Defensive patterns

Strategy: validation

Validate before calling

// re-validate the pane id at dispatch time, not when it was captured
if tab.get_pane_with_id(pane_id).is_none() {
    log::debug!("pane {pane_id:?} gone; dropping write");
    return Ok(false);
}

Type guard

fn pane_accepts_input(tab: &Tab, pane_id: PaneId) -> bool {
    tab.get_pane_with_id(pane_id).is_some()
}

Try / catch

// sync-panes fan-out must tolerate per-pane failure:
for pane_id in target_pane_ids {
    if let Err(e) = tab.write_to_pane_id(&key, bytes, false, pane_id, Some(client_id), None) {
        log::debug!("write to {pane_id:?} skipped: {e:#}");
    }
}

Prevention

When it happens

Trigger: write_to_pane_id invoked with a pane id captured earlier (input routing to a specific pane, sync-panes broadcast, completion notifications) after that pane exited, was closed, or its id was never valid in this tab. Sync-pane mode multiplies exposure since one keypress fans out to many pane ids.

Common situations: Sync-panes mode writing to panes that exit mid-session; mouse events routed to a pane that just closed; queued actions referencing dead pids; session resurrection replaying input against stale pane ids; plugins dispatching input by cached PaneId.

Related errors

AI-assisted analysis of zellij-org/zellij@98a0837077 (2026-08-16). Data as JSON: /api/errors/a46e4756e2dfdff5. Report an issue: GitHub.