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Common Issues with MCP (Model Context Protocol) WordPress Plugin and How to Fix Them (2025 Guide)

Common issues with MCP (Model Context Protocol) WordPress plugin and how to fix them

Introduction

At ControlF5, we have set up dozens of WordPress automation workflows using the MCP (Model Context Protocol) plugin. And while MCP is incredibly powerful, I will be honest, it’s not always smooth sailing.

Like any advanced automation system, MCP has its quirks. Sometimes it won’t trigger correctly. Sometimes it clashes with another plugin. And sometimes, the integration with n8n or Zapier just doesn’t behave as expected.

The good news? 90% of the issues we see can be fixed with a few simple checks and tweaks.

In this guide, I will share the most common MCP (Model Context Protocol) plugin issues we have encountered on the ControlF5 blog and across our client WordPress projects, and more importantly, how to fix them fast.

👉 If you are new to MCP, start with my Beginner’s Guide: What is MCP in WordPress?

1. MCP Plugin Not Activating

The Issue

Sometimes after installation, the MCP plugin just won’t activate. You will click “Activate” and either get an error or nothing happens.

Why It Happens

  • Outdated WordPress version
  • PHP compatibility issues
  • Conflicts with other automation plugins

Fix

  • Update WordPress to the latest version.
  • Ensure your PHP version is 7.4 or above (I recommend PHP 8+ for performance and compatibility).
  • Temporarily deactivate other automation plugins (like Uncanny Automator or Jetpack Automations) and test MCP alone.

📌 Pro Tip from ControlF5: Always test new plugins in a staging environment before activating them on your live blog.

2. MCP Messages Not Triggering in n8n

The Issue

You publish a blog, but nothing happens; n8n doesn’t receive any data.

Why It Happens

  • Incorrect webhook URL entered in MCP settings
  • MCP not mapping the right fields (title, URL, excerpt, etc.)
  • Security/firewall blocking webhook calls

Fix

  • Double-check the webhook URL you pasted into MCP (I have seen clients copy the test URL instead of the production one).
  • Map all essential fields (title, URL, author, excerpt).
  • If you are on managed hosting (like WP Engine or Kinsta), check that firewall rules aren’t blocking outgoing requests.

👉 Want a full workflow example? See Automating Your WordPress Blog with MCP and n8n.

3. Duplicate Actions Running

The Issue

You publish one blog post, but the automation runs twice (e.g., two Twitter posts, two Slack messages).

Why It Happens

  • MCP is firing both on “publish” and “update.”
  • n8n workflow isn’t filtering correctly.

Fix

  • In n8n, add a filter node so it only triggers when status = published.
  • In MCP, check if the trigger is tied only to the “publish_post” action, not “save_post.”

📌 At ControlF5, we always set a status filter in n8n to prevent duplicates.

4. Social Media Posts Not Formatting Correctly

The Issue

Your LinkedIn or Twitter posts look messy, wrong link, are missing a featured image, or have broken formatting.

Why It Happens

  • Featured image field not mapped in MCP
  • Rich-text fields are not handled correctly in n8n
  • Wrong API credentials for social platforms

Fix

  • Add the post thumbnail/featured image field when mapping MCP data.
  • Use n8n’s HTML-to-text or markdown nodes to clean up formatting.
  • Refresh or re-generate API tokens for LinkedIn/Twitter integrations.

👉 We faced this ourselves at ControlF5; our first Twitter automations looked broken until we added proper text cleaning in n8n.

5. Email Campaigns Not Sending

The Issue

You set up Mailchimp or Brevo campaigns via n8n, but emails never send.

Why It Happens

  • Post data is not mapping correctly into email fields
  • API key expired or permissions missing
  • Email draft created, but not triggered for sending

Fix

  • In n8n, make sure “Subject line” is mapped to your post title and “Body” to excerpt or content.
  • Generate a new API key and give it the right permissions.
  • Check if the campaign is being saved as “draft” instead of being auto-sent.

📌 ControlF5 Tip: We usually auto-create a draft email (for the marketing team to review) instead of sending it live instantly.

6. Conflict with Other Plugins

The Issue

MCP (Model Context Protocol) suddenly stops working after installing another plugin.

Why It Happens

  • Other plugins using the same WordPress hooks
  • Caching/optimization plugins interfering with webhooks

Fix

  • Disable other automation-related plugins and re-test MCP.
  • Clear cache (especially if using WP Rocket, LiteSpeed, or W3 Total Cache).
  • Exclude MCP webhook URLs from caching rules.

👉 We saw this with a healthcare client’s blog; their cache plugin was blocking webhook calls until we whitelisted them.

7. Security Restrictions on Hosting

The Issue

In some hosting environments, MCP calls never reach external tools.

Why It Happens

  • Host blocks outgoing webhooks for security
  • Firewall prevents API calls

Fix

  • Contact your host and request outgoing webhook/API access.
  • If possible, whitelist IP addresses for n8n or Zapier.

📌 At ControlF5, we have solved this for clients on GoDaddy, SiteGround, and Hostinger by adjusting firewall rules.

8. Performance Issues with Large Blogs

The Issue

On high-traffic sites, MCP automations slow down the admin dashboard.

Why It Happens

  • Too many simultaneous workflows
  • The hosting environment is not optimized

Fix

  • Move automations into asynchronous background processes (MCP supports this).
  • Scale hosting to handle webhook traffic.
  • Offload heavier workflows (like bulk social posting) to n8n queues.

👉 On the ControlF5 blog, we run 5+ workflows per post, but by queuing tasks in n8n, performance stays smooth.

Proactive Tips to Avoid MCP Issues

From years of building automation systems at ControlF5, here’s what I recommend:

  • Always test workflows in staging before pushing live.
  • Document your workflows, so if something breaks, you know what’s connected where.
  • Use error-handling in n8n (like retries or notifications).
  • Keep WordPress, MCP (Model Context Protocol), and n8n updated.

Conclusion

The MCP (Model Context Protocol) WordPress Plugin is incredibly powerful, but like any automation tool, it comes with its learning curve. Most issues are easy to solve once you know where to look.

At ControlF5, we have fixed these problems for both our own blog and client blogs across industries. And once set up correctly, MCP becomes a reliable, time-saving automation engine that scales effortlessly.

Quick Links:

If you are struggling with MCP issues, don’t waste hours troubleshooting; book a free consultation with ControlF5. My team will audit your setup, fix the problems, and design a system that just works.

Frequently Asked Questions (FAQ)

1. Why is my MCP plugin not connecting to n8n?

This usually happens due to incorrect API credentials or missing authentication. Double-check your API key, ensure you’re using the correct authentication type (Bearer/Auth), and confirm your n8n instance is live and accessible.

2. What should I do if MCP fails to publish posts automatically?

First, verify that your WordPress cron jobs are running properly. Then, check your workflow in n8n for any broken nodes or incorrect mapping. Updating MCP to the latest version often resolves publishing glitches.

3. How do I fix MCP errors when integrating with third-party apps?

Most errors stem from misconfigured endpoints or permission issues. Ensure the connected app allows API access, review the endpoint URL, and check that the MCP plugin settings match the third-party app’s API requirements.

4. Is there a way to prevent MCP plugin performance issues on large blogs?

Yes. For high-traffic websites, optimize your server resources, use caching plugins, and avoid overly complex workflows in n8n. Splitting large automation tasks into smaller workflows also helps prevent slowdowns or timeouts.

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Anurag Pandey

I lead ControlF5, a Top Rated Plus agency specializing in WordPress, Shopify, and GoHighLevel development. With over 4,000+ successful projects on Upwork, 150+ verified reviews on Clutch, and 300+ completed projects on Freelancer, my team and I help global brands grow through strategic design, automation, and SEO excellence. Holding a B.E. in Computer Science, I’m passionate about combining AI-driven workflows and GoHighLevel automations to simplify marketing, boost organic SEO, and scale customer engagement. I actively share insights across web development and AI communities to help others navigate the evolving digital landscape. For me, web design isn’t just about aesthetics, it’s about building SEO-optimized, conversion-ready experiences that create measurable business growth in the AI-powered era.
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