Users encounter intermittent 404 errors after clicking "Continue" on a Secure Web Gateway (SWG) warn page instead of being allowed through as intended. This issue occurs during normal policy flow when SWG warn pages are triggered, impacting user web access. The problem manifests as users hitting the SWG warn page via desired policy implementation, but after clicking "Continue" they receive 404 errors instead of proceeding to their intended destination.
Technology: Solution Support (SSPT - contract required)
Sub-technology: Secure Access
Product Family: SECACCS
Affected Domain: block.sse.cisco.com
The issue has been resolved in CSC version 5.1.16, which is now available on CCO (Cisco Connection Online). The resolution involved modifications to DNS handling and response processing for the affected domain.
Step 1: Upgrade to CSC 5.1.16
Download and install CSC version 5.1.16 from CCO, which contains the fix for the DNS record handling issue.
Step 2: Verify DNS Response Changes
The DNS AAAA response for block.sse.cisco.com has been modified to not use mapped IPs, eliminating the root cause of the issue.
Step 3: Test SWG Warn Page Functionality
Verify that users can successfully click "Continue" on SWG warn pages without encountering 404 errors.
If the issue persists or for diagnostic purposes, collect the following logs.
https://www.cisco.com/c/en/us/support/docs/security/secure-access/221240-troubleshoot-and-collect-basic-informati.html
DART logs with maximum debug enabled
Network packet captures (pcap)
KDF logs
HAR (HTTP Archive) files from browser sessions
The issue occurred due to DNS records for block.sse.cisco.com in the internal DNS cache being overwritten by duplicate DNS records with randomized TTLs (Time To Live values). This DNS corruption caused the SWG warn page redirection mechanism to fail, resulting in 404 errors when users attempted to continue through the warn page. The DNS handling inconsistencies prevented proper resolution of the domain used for the warn page functionality.
| Revision | Publish Date | Comments |
|---|---|---|
1.0 |
27-May-2026
|
Initial Release |