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MCP Troubleshooting: Connection, Cloudflare & SSL Issues - AIWU – AI Plugin for WordPress
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MCP Troubleshooting: Connection, Cloudflare & SSL Issues

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Byaiadmin

MCP connection failing? This guide covers the most common causes — Cloudflare blocks, SSL errors, token issues, and server configuration — with specific fixes for each.

In this article: Quick Diagnostics · Cloudflare Issues · SSL Issues · Token & Auth Issues · Other Causes

Before You Start

Related guides:

Before You Troubleshoot

First, do a quick connectivity test. Open this URL in a browser (replace with your domain):

https://yoursite.com/wp-json/aiwu/mcp/v1/discovery

You should see JSON output (starting with {"name":"AIWU MCP Server"...}). If you get an error instead, that tells you what’s wrong.

What you see Likely cause Jump to
JSON output Endpoint works — issue is in the AI client config Token & Auth Issues
403 Forbidden Cloudflare or security plugin blocking Cloudflare Issues
SSL/HTTPS error Certificate problem SSL Issues
404 Not Found Plugin not active, or permalinks not flushed Other Causes
500 Server Error PHP error on server Other Causes
Connection timeout Server or Cloudflare timeout Cloudflare Issues

Quick Diagnostics Checklist

  • ☐ AIWU plugin is active (not just installed)
  • ☐ HTTPS/SSL is enabled on your site (not HTTP)
  • ☐ MCP is enabled in AI Copilot → MCP → Settings
  • ☐ WordPress permalinks are set (not “Plain”) — Settings → Permalinks → Save
  • ☐ Your MCP token hasn’t expired or been regenerated
  • ☐ No conflicting security plugins blocking /wp-json/ paths

Cloudflare Issues

Cloudflare is the most common cause of MCP connection problems. Cloudflare’s security rules can block or slow SSE (Server-Sent Events) connections, which MCP uses.

Issue: 403 Forbidden from Cloudflare

How to check: Open browser DevTools → Network tab → click the failed request → look for the cf-ray header in the response. If present, Cloudflare is involved.

Fix: Add a Cloudflare WAF bypass rule for MCP paths.

  1. Go to Cloudflare Dashboard → [your domain] → Security → WAF → Custom Rules
  2. Click Create rule
  3. Set: URI Path contains /wp-json/aiwu/mcp/
  4. Action: Skip → Skip all remaining custom rules
  5. Save and deploy

Issue: SSE Connection Timing Out (Cloudflare 524 error)

Cloudflare has a default 100-second timeout for origin connections. MCP uses persistent SSE connections that can exceed this.

Fix: Create a Cloudflare Page Rule for the MCP path:

  1. Rules → Page Rules → Create Page Rule
  2. URL pattern: yoursite.com/wp-json/aiwu/mcp/*
  3. Setting: Disable Performance and Cache Level: Bypass
  4. Save
💡 Alternative: If you have Cloudflare Pro or higher, you can increase the timeout limit under Network → Maximum HTTP/3 Connection Duration. Free plans are limited to the 100-second default.

Issue: Cloudflare Bot Fight Mode blocking Anthropic’s servers

When Claude.ai’s servers make MCP calls, Cloudflare may identify them as bots and block the connection.

Fix: Add Anthropic IP ranges to your Cloudflare IP allowlist, or create a WAF rule allowing requests with the Anthropic User-Agent:

  1. Security → WAF → Custom Rules → Create rule
  2. Condition: HTTP User Agent contains claude
  3. Action: Allow

SSL Issues

Issue: SSL certificate error (“SSL_ERROR_BAD_CERT”)

How to check: Go to SSL Labs and test your domain. A grade of A or B is required. F grade or “Certificate not trusted” means Claude.ai will refuse the connection.

Fix options:

  • Install a free Let’s Encrypt certificate via your hosting control panel
  • If using Cloudflare, set SSL mode to Full (strict) in SSL/TLS → Overview
  • Renew expired certificate through your hosting provider

Issue: Mixed content (HTTP resources on an HTTPS page)

Fix: In AIWU settings, make sure the site URL is set to https://. Go to WordPress Admin → Settings → General and verify both WordPress Address and Site Address start with https://.

Token & Authentication Issues

Issue: “Unauthorized” or 401 error when Claude calls MCP tools

How to check: Test your token manually:

curl -H "Authorization: Bearer YOUR_TOKEN" 
  "https://yoursite.com/wp-json/aiwu/mcp/v1/tools"

If you get a 401, the token is invalid or expired.

Fix: Go to AI Copilot → MCP → Settings, click Regenerate Token, then update the token in your AI client config.

Issue: OAuth token expired (Remote MCP)

Remote MCP OAuth tokens are valid for 30 days of inactivity.

Fix: In Claude.ai settings, disconnect and reconnect the AIWU integration. The OAuth flow will issue a new token automatically.

Issue: Token works in browser but not in Claude Desktop config file

Fix: Check your mcp.json for:

  • No extra spaces around the token
  • Valid JSON syntax (use jsonlint.com to validate)
  • Token on one line — no line breaks inside the string

Other Causes

Issue: 404 Not Found on MCP endpoints

Fix: Go to WordPress Admin → Settings → Permalinks and click Save Changes (no need to change anything — just saving flushes rewrite rules). Then test the endpoint again.

Issue: Security plugin blocking MCP

Plugins like Wordfence, iThemes Security, or WP Cerber can block REST API access.

Fix: Temporarily disable the security plugin and test. If MCP works, whitelist the path /wp-json/aiwu/mcp/ in your security plugin settings.

Issue: PHP memory limit causing 500 errors

Fix: Add to your wp-config.php:
define('WP_MEMORY_LIMIT', '256M');

Still stuck? Enable AIWU debug logging in AI Copilot → Settings → Advanced → Enable Debug Log, reproduce the error, then check the log at AI Copilot → Logs for specific error messages. Contact support with the log.

What’s Next

Last verified: AIWU v.4.9.2 · Updated: 2026-02-25

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