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N-able N-Central | 404 Response

N-Central, N-able, 404, IndexAction.Action., 404 - failing on IndexAction.Action on API call", N-Able N-Central Error

Updated over a week ago

Overview 💥

A common configuration error causes the N-Central inspector to return 404 errors with messages that reference IndexAction.Action. This happens when the Inspector’s Instance URL field contains a full path (for example /IndexAction.action) or a protocol (https://) rather than the base domain (FQDN). The Inspector builds API calls from the Instance URL; if it contains path components the resulting API request is invalid and returns 404.

This article explains why that occurs, how to confirm the misconfiguration, step-by-step remediation, additional checks (DNS, ports, redirects), and what to collect if you need to escalate to Support.

Why this happens? 🤔

  • Incorrect Instance URL format: The Inspector expects only the domain (and optional port) — not protocol or path. Example incorrect value: https://integration.n-able.com/IndexAction.action.

  • Trailing slashes or extra path segments appended inadvertently cause Inspector to call wrong endpoints.

  • Invisible whitespace or encoding issues (copy/paste) can alter the final API call.

  • DNS resolution issues or host redirects can alter the expected API endpoint and lead to 404s.

  • Reverse proxies / rewrite rules on the customer side may intercept and modify paths.

  • Custom ports (non-standard) not specified properly can cause a wrong target to be reached.

Quick fix 😉

Edit the Inspector instance and set Instance URL to only the domain (optionally with port):
​integration.n-able.com (NOT https://integration.n-able.com/IndexAction.action)

Save, then re-run the inspector.

Step-by-step resolution 👨‍💻

1️⃣ — Confirm the Instance URL value

  • Go to Admin → Inspectors → N-Central → [your inspector] → Edit.

  • Ensure the Instance URL field contains only domain and optional port:

    • ✅ Correct: integration.n-able.com or integration.n-able.com:8080

    • ❌ Incorrect: https://integration.n-able.com/IndexAction.action or integration.n-able.com/IndexAction.action/

  • Remove any leading http:// or https://, any trailing slash, or any path.

2️⃣ — Save and re-run the Inspector

  • Save configuration and run the inspector immediately (use Clear Cache + Debug Mode if the failure persists to collect fresh logs).

3️⃣ — Verify the exact API call the inspector is attempting

If the issue persists, examine the inspector debug log for the exact URL being called (look for request URLs and the 404 response). This will confirm whether a path is still being appended.

4️⃣ — Test connectivity & resolution from the Agent host

Run the below checks from the same machine where the Liongard Agent runs — this reproduces the agent’s network view:

Basic DNS / reachability

# Linux/macOS 
nslookup integration.n-able.com 
ping -c 4 integration.n-able.com  

# Windows PowerShell 
Resolve-DnsName integration.n-able.com 
Test-Connection integration.n-able.com -Count 4

Check HTTP(S) response / redirect behavior

# from Linux/macOS 
curl -I https://integration.n-able.com/   # check headers 
curl -I https://integration.n-able.com/IndexAction.action  # see server's behavior

# Windows PowerShell
Invoke-WebRequest -Uri "https://integration.n-able.com" -Method Head

Look for:

  • DNS resolving to correct IP.

  • 200 or redirect (3xx) on base URL.

  • If the server redirects base URL to a path, note the redirect target.

5️⃣ — Confirm there are no invisible characters or whitespace

  • Re-type the Instance URL manually (don’t paste).

  • Remove trailing spaces.

6️⃣ — Check for custom ports or proxies

  • If your N-Central instance uses a custom port, include it: integration.n-able.com:8080.

  • If there is a reverse proxy or load balancer, validate its rewrite rules aren’t altering or requiring full path values.

7️⃣ — If redirects are present

  • If curl -I shows a redirect from base domain to a path, confirm whether your environment requires a proxy or header adjustments. Provide the redirect details when contacting Support.

Troubleshooting quick reference 🤩

Symptom

Likely cause

How to check

Action

404 referencing IndexAction.action

Instance URL contains path or protocol

Inspect Instance URL in Inspector settings

Remove path / protocol (use only domain: integration.n-able.com)

404 persists after correction

Agent still hitting wrong URL

Check Inspector debug log for called URL

Confirm saved config, clear cache, re-run in debug; retype URL

DNS fails / wrong IP

DNS misconfiguration or propagation

nslookup / Resolve-DnsName from agent host

Fix DNS; update hosts if needed; re-run inspector

Redirects to path from base domain

Web server / proxy rewrite rules

curl -I https://domain to inspect Location header

Provide redirect details to support; ensure proxy is configured correctly

Uses non-standard port

Port not specified in Instance URL

Test-NetConnection -Port or nc -vz from agent host

Add :port to Instance URL or open firewall ports

Useful commands 🚀

✅ Linux / macOS

nslookup integration.n-able.com 

ping -c4 integration.n-able.com 

traceroute integration.n-able.com 

curl -I https://integration.n-able.com 

curl -I https://integration.n-able.com/IndexAction.action 

nc -vz integration.n-able.com 443

✅ Windows (PowerShell)

Resolve-DnsName integration.n-able.com 

Test-Connection integration.n-able.com -Count 4 tracert integration.n-able.com 

Invoke-WebRequest -Uri "https://integration.n-able.com" -Method Head 

Test-NetConnection -ComputerName integration.n-able.com -Port 443

Best practices 🧑‍🏫

  • Only set Instance URL to the base FQDN (FQDN[:port]). Do not include http(s):// or any path.

  • Keep a documented example in your runbook to avoid copy/paste mistakes.

  • When using custom ports, include them as domain.tld:port.

  • After any N-Central migration or DNS change, re-verify inspectors’ Instance URLs and test from the agent host.

  • Use Clear Cache + Debug Mode when validating fixes to get fresh logs.

When to contact Support 🦁

Contact Liongard Support if:

  • The Instance URL is correctly set to the base domain and you still receive 404.

  • The inspector debug log shows the agent is calling a path that you cannot explain.

  • There are redirects or proxy rewrite rules that you cannot change and you need assistance mapping the correct configuration.
    Include the items listed above.

✅ What to collect for Support

  1. Inspector debug log (run Clear Cache + Debug Mode and attach logs).

  2. Screenshot of Inspector configuration showing your Instance URL.

  3. curl -I or Invoke-WebRequest -Method Head outputs from the agent host for both root and /IndexAction.action.

  4. nslookup / Resolve-DnsName and traceroute from agent host.

  5. Any recent changes to N-Central (version, migration, proxy/load balancer).

  6. If applicable, the redirect Location header returned by the server.

Providing these items will speed triage.

References & external links 📚

Third-Party Link Disclaimer ‼️

We may reference external third-party resources solely as additional guidance.

Liongard does not own, control, or guarantee the accuracy, security, or reliability of third-party sites. Please use them at your own discretion and risk.

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