Troubleshooting Application 404 Errors in Sisense [Linux Self-Hosted]

Introduction

To provide both users and Sisense support engineers with a consistent approach to diagnosing and resolving unexplained 404 (Not Found) errors observed in the browser when loading dashboards, data models, or other areas of the application.

Symptoms

• Browser developer tools (HAR or network tab) show 404 responses for valid-looking API requests (e.g., /api/v1/datasources/, /api/datasecurity/).
• 404s occur during normal product usage (e.g., opening dashboards or viewing data security rules).
• X-Request-ID from failing requests cannot be found in any Sisense backend service logs.
• Errors persist after product upgrades.

Likely Root Causes

1. Intermediary network devices (NetScaler, firewalls, proxies) are dropping or misrouting requests.
2. URL rewrite or filtering policies are configured to block unknown or unused API paths.
3. Frontend logic makes background calls to connectors that are not actively in use (e.g., Google Sheets).
4. Invalid or legacy connector references are cached in the browser or data model.

Recommended Troubleshooting Steps:

1. Reproduce and collect a HAR file:
• Capture a HAR file during the failing operation.
• Look for 404s and note the request URL, path, and query params.
  
  
2. Check for backend traceability:
• Locate the X-Request-ID of the 404 request in backend logs (query, galaxy, etc.).
• If no log exists, the request likely never reached Sisense.
  
  
3. Test direct access (bypassing intermediaries):
• Access Sisense directly via its internal IP or hostname.
• If the error disappears, the issue lies in your firewall/NetScaler config.
  
  
4. Inspect intermediary logs and rules:
• Inspect NetScaler (or firewall) logs.
• Check for dropped/blocked requests or URL rewrite rules affecting API routes.
• Ensure whitelist policies include all necessary Sisense API endpoints.
  
  
5. Check unused connectors:
• If the 404s reference an unused connector (like Google Sheets), disable it in the Sisense connector configuration.

Conclusion 

If you see browser 404s with no corresponding entries in Sisense logs, investigate intermediate infrastructure (firewalls, proxies, load balancers). These devices can block requests silently and create symptoms that appear to originate from the application layer.