Change WordPress Themes (The Safe Way) – Fehler7 WordPress Pros

Today’s guide article is about WordPress themes and how to change them. We strongly recommend that you read the entire article, because changing a theme also harbors dangers.

What are WordPress themes?

WordPress themes determine the design of your website. Themes are often incorrectly referred to as “templates”. However, that is not correct. A template only determines the design and structure of a certain type of page, for example: the start page, all article pages or all category pages. Themes are a collection of all templates. In addition, you can also store individual programming in your WordPress theme (in the functions.php on your server).

Change WordPress theme: Here’s how

You can easily change WordPress themes via the backend (the admin area) without any programming knowledge:

  1. To do this, log into the WordPress admin area (www.yoursite.tld/wp-admin).
  2. Click on “Design” in the left menu bar.
  3. WordPress will now show you all installed themes.
  4. Hover over the theme you want to use. An “Activate” button will then appear.
  5. Click on “Activate”. Complete.

Illustrated instructions

Click on “Design”.

WordPress theme overview.

The dangers of changing a theme

Alright, now you know how to change your WordPress theme. However, the devil is often in the details. If you change the theme, nasty surprises can await you. Here are a few in brief:

  • The new theme is buggy or incompatible with your WordPress version or an installed plugin. With a lot of bad luck you now only see a white page (see also our article WordPress white page) and can no longer log into the admin area.
  • It is also possible that certain parts of your website are broken or some functions are no longer working. Some of these are functions that you do not necessarily associate with the theme. For example, the contact form can no longer work with the new theme.
  • It gets really scary if your previous theme worked with a page builder. Pagebuilders extend the WordPress editor. With them, more complex pages can be built much more easily. Well-known page builders are: Visual Composer WP Bakery, Elementor, Divi or Beaver Builder. If your new theme uses a different page builder, there may be problems.

How to safely change your WordPress theme

So we have now established that the change in theme harbors some potential dangers. So how to safely change a WordPress theme? First of all, you should never change a theme live. Instead, create a test environment (also called a staging environment).

Step 1: Create test environment

First create a test environment. There are plugins that do this for you. For example, there is the plugin Duplicator, with which you can quickly do this yourself. An exact copy of your website (a clone) is then created. Only the URL under which the test environment runs differs from your live website. For example, you can place the test environment under a subdomain such as: staging.yoursite.tld.

Step 2: Theme preview

In WordPress, go to “Theme” in the left menu, hover over your desired theme, and click “Live Preview”. WordPress will now show you a preview of the theme. This has two advantages: 1. You can now see whether you like the new theme at all. 2. You can see if the new theme causes critical errors that would break your website.

Step 3: Change Theme

If the theme passed the first test, it can now be changed. Click on “Theme” again as described above, hover over the respective theme and click on “Activate”.

Step 4: Quality Control and Troubleshooting

Now you should put your WordPress website through its paces on the test environment. Check all important pages and templates (article templates, page templates, category / archive templates etc.). You should also test all important functions, for example forms. If you are familiar with PHP programming, you should enable debug mode in wp-config.php. To do this, set the constant “WP_DEBUG” to “true”:


Now you will see PHP errors and warnings that can alert you to possible problems.

Step 5: Go live

Does the new theme work as expected? Then you can go live. Use the Duplicator plugin again to copy the test environment to the live environment. Please note when going live: If you have made changes to the live environment in the meantime, you will have to update them later.


Here’s how you can safely change your WordPress theme:

  1. Create a test environment: Use the Duplicator plugin for this.
  2. Theme preview: Use WordPress’ own preview function to identify critical errors in advance.
  3. Activate new theme: Activate the new theme on the test environment
  4. Quality control and troubleshooting: Check all essential functions on the test environment.
  5. Go live: If everything works, go live with the test environment.

You need help around WordPress?

As always, if you need help, feel free to contact our 24/7 WordPress support. We are happy to help you with all matters relating to your website.