Skip to main contentLog Files
When issues persist, use the following techniques to diagnose the root cause. The goal is to capture enough evidence (logs, traces, repro steps) for quick resolution.
Log files can be opened from the ribbon by clicking the Version split button and then the log file commands.
Inspect Logs
- VSTO Logs –
%LOCALAPPDATA%\X21\Logs\X21.log. Look for Excel API warnings, HTTP listener errors, or WebView bridge issues.
- Deno Logs –
%LOCALAPPDATA%\X21\X21-deno\Logs\deno-<machine>.log. Check for router errors, Claude API failures, or tool execution details.
WebView Diagnostics
- Press
Ctrl + Shift + I inside the task pane (if developer tools are enabled) to open DevTools for network inspection and console logging.
- Inspect WebSocket frames to verify message payloads between the UI and backend.
- Confirm Supabase auth responses and storage writes using the Application panel.
Collecting detailed diagnostics shortens turnaround time when collaborating with engineering or support teams. 
