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IIS Troubleshooting Overview
Use this page as the primary troubleshooting hub for IIS-related issues during Nodinite installations and upgrades. It helps you route quickly from symptom to the right fix for Authentication, Certificate/TLS, URL Rewrite, IIS Features, and HTTP Errors.
Understanding IIS in a Nodinite Installation
IIS fronts the web-facing components and controls TLS termination, Windows Authentication behavior, and request filtering. Most IIS incidents can be classified into one of these areas:
- Authentication negotiation (Kerberos/NTLM, Intranet Zone, SPN)
- Certificate and TLS configuration
- Missing IIS Windows Features or modules
- HTTP method or handler conflicts (for example HTTP 405)
- Legacy URL Rewrite behavior in upgraded v6 environments
Quick Triage Workflow
flowchart TD
A[Start IIS troubleshooting] --> B{Can users access and sign in?}
B -->|No| C[Review IIS Authentication settings]
C --> D[Validate Kerberos vs NTLM, Intranet Zone, SPN]
B -->|Yes| E{HTTP error shown?}
E -->|405| F[Fix WebDAV or handler mapping]
E -->|Other| G[Check IIS Windows Features and logs]
B -->|Intermittent or slow| H[Run NTLM vs Kerberos diagnostics]
H --> D
A --> I{TLS or certificate warnings?}
I -->|Yes| J[Run hardening and TLS troubleshooting]
A --> K{Upgraded from v6?}
K -->|Yes| L[Check legacy URL Rewrite redirect rule]
Symptom-to-Guide Routing
| Symptom | Most likely area | Start here |
|---|---|---|
| Repeated credential prompts or failed sign-in | Windows Authentication negotiation | IIS Authentication settings |
| Slow responses (4-30 seconds), random auth delays | Kerberos fallback to NTLM, SPN, Intranet Zone | NTLM vs Kerberos Authentication |
| HTTP Error 405.0 when using PUT/DELETE | WebDAV or handler mapping conflict | HTTP Error 405.0 - Method Not Allowed |
| Missing modules or unexpected IIS behavior | IIS Features/roles not installed correctly | IIS Windows Features |
| Redirect to old v6 HTTPS address or old ports | Legacy URL Rewrite rule still active | IIS URL Rewrite – Legacy v6 Redirect |
| Certificate warnings, TLS handshake issues, hardening gaps | Certificate/TLS hardening and trust chain | How to perform hardening on your Nodinite installation |
Guide Index
HTTPS and TLS Hardening
- How to perform hardening on your Nodinite installation - Main guide for active installations.
- How to perform hardening on your Nodinite v6 installation - Legacy guide for v6 environments.
- Development Certificates - Self-signed certificate workflow for non-production use.
- TLS Troubleshooting - CRL/OCSP and loopback troubleshooting.
- HTTP Security Headers - HSTS, CSP, and related hardening headers.
- Access Controls and Vendor Policy - Access and security governance.
- Key Management, Backup and Data Residency - Key lifecycle and regional/compliance guidance.
Authentication and Identity
- IIS Authentication settings - Baseline configuration for Windows Authentication.
- NTLM vs Kerberos Authentication - Performance and negotiation diagnostics.
- SPN - IIS Application Pool - SPN registration path when app pools use domain identities.
- IIS Windows Features - Required server features for stable behavior.
URL Rewrite and Legacy Migration
- IIS URL Rewrite – Legacy v6 Redirect - Remove stale redirect behavior after v6-to-v7 transition.
HTTP Errors
- HTTP Error 405.0 - Method Not Allowed - WebDAV and handler mapping remediation.
Next Step
- Start with IIS Authentication settings if users cannot sign in.
- If authentication is slow, run NTLM vs Kerberos Authentication and validate Intranet Zone and SPN.
- If TLS or certificate issues appear, continue with How to perform hardening on your Nodinite installation.
Related Topics
- Install and Update Troubleshooting Overview
- Windows Server Troubleshooting Overview
- SQL Server Troubleshooting Overview