Browser shows HTTP Error 403.503 – Forbidden, detailed error references IpRestrictionModule
You may encounter HTTP Error 403.503 when accessing the Snow License Manager website or when services communicate with IIS APIs. This error can occur when IP filtering is misconfigured. Because the IpRestrictionModule runs early in the IIS request pipeline, IIS may reject requests before they reach the application or authentication and authorization settings are evaluated.
Website access symptoms
- Browser shows “HTTP Error 403.503 – Forbidden”
- Browser displays: “You do not have permission to view this directory or page.”
- IIS error page details:
- Module: IpRestrictionModule
- Notification: BeginRequest
- Error Code: 0x80070005
API communication symptoms
- API calls to IIS fail, returning “403 Forbidden”
- Background services cannot reach IIS endpoints
- Server-to-server requests fail, even on the same host
- Functionality relying on internal API calls stop working
To fix this, add the API endpoint (server IP) and localhost IP to the restriction address allow list.
IMPORTANT: Obtain confirmation from the server security team before implementing these changes.
Explicitly allow localhost and the server IP addresses at the site level.
- Open IIS Manager → Sites → Snow License Manager site.
- Open IP Address and Domain Restrictions (ensure this feature is enabled in the server configuration).
- Add Allow Entry for the following:
- 127.0.0.1
- ::1 (IPv6 loopback; include this address because some servers may use IPv6 for local requests)
- Server IP addresses
- Restart the site (Manage Website → Restart).
Server-level rules can still block requests that are allowed at the site level. Review IIS Manager → [Server name] → IP Address and Domain Restrictions, and verify that localhost, the server IP addresses, and the appropriate administrative subnets are allowed.
Once these settings are applied and validated, local web access and API communication should be restored.
