Fixing 421 Misdirected Request Errors on Multilingual WordPress Sites Using Apache & NGINX

All of a sudden, we encountered an intermittent but critical issue affecting multiple domains hosted on our cPanel server with both Apache and NGINX enabled. The issue manifested as random 421 Misdirected Request errors on a multilingual agency website as well:

• 🔗 https://www.nordicdigisolutions.com

• 🔗 https://www.nordicdigisolutions.no

Despite a valid SSL setup and clean redirects, HTTPS requests were occasionally misrouted or rejected. This post documents our full diagnostic journey and resolution, and may serve as a reference for others facing similar issues.

Symptoms We Noticed

• ❌ Random 421 Misdirected Request errors appearing only on HTTPS pages

• 🌐 Affected both domains: .com and .no

• 🔁 Issue was intermittent — some visits worked, others failed

• ✅ All redirects (non-www → www, HTTP → HTTPS) appeared to function correctly

• 🛑 Despite that, the final destination would sometimes return a 421 error page

🔍 Investigation Steps

1. Checked Apache Virtual Hosts

• Both domains were configured correctly in cPanel

• Each domain had its own SSL certificate issued via AutoSSL

• DocumentRoot paths were separate, avoiding any aliasing or overlap

2. Tested Redirection Rules

• .htaccess rules were in place for:

• Enforcing https://

• Redirecting non-www to www

• Cloudflare Page Rules also mirrored this logic for consistency

• We confirmed there were no redirect loops, misroutes, or invalid targets using redirect checkers

3. Cloudflare Debugging

• DNS Settings were correct — both domains pointed to our server via Cloudflare proxies

• SSL/TLS settings were set to “Full” (not Flexible)

• Used response header analysis to trace:

• Redirect flow

• Origin IP matches

• Certificate validity

• Conclusion: Nothing abnormal was found in Cloudflare’s routing behavior

4. Validated SSLs in cPanel

Under SSL/TLS → Manage SSL Sites, both domains had:

• Correct certificate bindings

• Proper chain (Root, Intermediate, Domain)

• Valid expiration dates

• Certificates were not shared or reused between domains

5. Tried Disabling Caching Temporarily

• Cleared Cloudflare cache

• Purged WP Rocket cache entirely

• Retested with incognito/private browsing and curl requests

• Outcome: The 421 error still occurred randomly, suggesting caching was not the root cause

6. Checked Apache Virtual Hosts (Again)

• Both domains were configured correctly in cPanel with separate SSL certificates

• Same /public_html/ DocumentRoot was used for both .com and .no

• Polylang was used to manage language-specific versions of the site within a single WordPress installation

• No alias or misconfiguration was found in the VirtualHost setup

🛑 Root Cause

After hours of configuration checks and log reviews, the root cause wasn’t within our Cloudflare settings, redirects, caching, or even Apache VirtualHost declarations. Instead, the breakthrough came through Namecheap support.

They confirmed that the issue was linked to a recent EasyApache 4 update that introduced a conflict when NGINX is used as a reverse proxy in front of Apache, which was exactly our setup.

The critical detail:

• The problem only occurred for HTTPS traffic

• It specifically affected requests proxied via EA-NGINX

• The bug caused Apache to misroute requests between domains, resulting in 421 Misdirected Request errors even when SSLs were valid and domains were separate

📌 Reference:

The official cPanel documentation later confirmed this was a known issue:

Websites show 421 Misdirected Request error while using EA-NGINX or other proxies

✅ The Fix

Once we identified the source of the issue, the fix was straightforward. We applied the official cPanel patch by executing the following command on the server:

/scripts/upcp

This command:

• Updates all EasyApache (EA4) packages

• Applies the cPanel patch for NGINX-to-Apache SNI routing issues

• Restarts services gracefully

After the update and restart:

• The intermittent 421 errors on both .com and .no domains were completely resolved

• All HTTPS requests consistently routed to the correct virtual host

• No further misrouting or caching anomalies observed

We then re-verified everything:

• DNS and redirects worked flawlessly

• Cloudflare behaved as expected

• No .htaccess conflicts remained

• Polylang was unaffected

Lessons Learned

Managing a multi-domain setup on a cPanel server that uses NGINX as a reverse proxy over Apache requires close attention, especially after EasyApache 4 (EA4) or similar service updates. Even small backend changes can introduce SSL-related bugs that aren’t immediately obvious.

Key takeaways from our experience:

• EasyApache + NGINX setups must be retested after updates: Even when no visible config changes are made, backend handling of SSL (SNI) can break silently.

• Cloudflare can’t fix backend SSL mismatches: Even though Cloudflare handled our DNS, caching, and TLS termination perfectly, the final SNI mismatch occurred between NGINX and Apache, which is outside Cloudflare’s control.

• Diagnostic tools matter: Tools like httpstatus.io, Chrome DevTools → Network tab, and direct curl tests helped us follow the redirect flow and isolate when/where the issue occurred.

• VirtualHost separation is critical: Having dedicated SSLs and clear separation in Apache’s virtual hosts for each domain helped rule out misconfiguration early in the process.

Stack Overview

To help others debug similar setups, here’s a snapshot of our technical stack:

• Hosting: VPS (from Namecheap)

• Web Server Stack: Apache (via cPanel) with NGINX (EasyApache 4 Reverse Proxy)

• CDN + Proxy: Cloudflare (Full SSL mode)

• CMS: WordPress, running a multilingual setup using Polylang

• SSL Certificates: AutoSSL (Let’s Encrypt via cPanel)

This hybrid stack offers performance and flexibility, but also comes with complexity that must be monitored closely.

🔁 What’s Next

We’ve added this situation to our internal post-deployment checklist for any site using:

• Multi-domain WordPress sites

• Language-specific domains (e.g., .no + .com)

• NGINX → Apache reverse proxy configurations

• Post-EA4 update verifications (especially SSL/SNI routing)

We’ll also monitor EA4 changelogs closely and perform SNI tests proactively after every server update.

🔑 Key Takeaways

• 421 errors can occur in NGINX + Apache (EA4) setups after EasyApache updates

• Issue affects HTTPS traffic only, even when SSL and redirects are valid

• Errors are intermittent and may escape normal QA checks

• Applying /scripts/upcp resolves the bug by patching SNI handling

• Tools like httpstatus.io and browser DevTools (Network tab) are essential for tracing redirect chains and pinpointing misrouting