REST API Issue Notice in Trellis

What is this message, and what do you do when you see it on your site?

Jacob Feltner avatar
Written by Jacob Feltner
Updated over a week ago

You may have noticed one of the below issue messages popping up on your Trellis site in the backend:

Trellis is having trouble with your REST API. Critical CSS has been disabled.

Trellis will continue attempting to reach your REST API and Critical CSS will be enabled if Trellis can connect to your REST API.

Why does it matter?

Critical CSS is one of Trellis's main optimizations that makes it so fast, and it's very important for speed and Core Web Vitals.

All of this means that you definitely want to give your attention to this notice right away.

What does this notice mean?

The short answer is your site's Critical CSS is having trouble and may not be serving because it's being blocked from accessing the necessary API (the service that allows us to deliver Critical CSS on your site). This is means that your site may have a firewall, or bot blocking enabled that is blocking Trellis from accessing the REST API.

How to get rid of the REST API warning?

First, try clearing your Trellis Cache in the Mediavine Trellis → Advanced menu under → Permanent Actions:

Next, check for any bot blocking, or firewall plugins such as iThemes Security, WordFence, or Titan Anti-Spam. Be sure to set your Firewall settings to "Learning Mode" for WordFence and Titan Anti-Spam. For iThemes Security be sure that the Rest API setting is Set to Default Access.

If you don’t have any bot blocking or firewall plugins, check with your host to see if your server has bot blocking or firewall settings enabled. If so, you can provide your host with the information below and ask them to “allowlist the Trellis Services API in your firewall”:

'X-MV-Trellis-Services': 'trellis-services'

'User-Agent': 'Trellis-Services'

Email the Trellis Team for Help

Since it's important for your Critical CSS to be working, it's best to address this issue when it comes up. If you run into any issues don’t hesitate to reach out to us, our expert team will be happy to help.

Reach out to and we'll be in touch to get started!

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