How to Update WordPress Theme Without Losing Customisations

Let’s be honest: updating a WordPress theme is bad enough. Updating a WordPress theme which has customisations? Nightmare.

WordPress updates always carry the risk of crashing your site. But theme updates go one step further, when you risk losing all the customisation you’ve carefully added.

The good news is: there are several ways to handle this. In this article, we’ll show you how to update a WordPress theme without losing your custom changes, step by step.

TL;DR: The safest way to update a theme in WordPress is to use a staging site to test the update first. Create a staging site in minutes with BlogVault, from an automatic, full site backup.

Why update your WordPress theme?

You might be hesitant to update your WordPress theme, especially if everything seems to work fine. But it’s worth the effort:

1. Compatibility: New WordPress versions might not work well with older themes, so updates ensure smooth operation.
2. Security: Updates fix security gaps that can make your site vulnerable to hacks. Outdated themes are often the reason 95% of attacks succeed.
3. Better performance: Regular updates improve site speed and squash bugs, enhancing user experience and SEO.
4. Feature upgrades: New features, like more content blocks, keep your site exciting and engaging.

📝 Before we jump into the steps, backup your WordPress site. It is a non-negotiable insurance policy for your site, and it will literally take a few minutes to do.

Step 1: Pre-update checklist

Before updating a WordPress theme, there are a few things you should do to ensure that the update goes as smoothly as possible. Think of it as guaranteeing success.   

• Take a full site backup. As you will see going forward, there are many ways to update a theme, depending on how your site is set up. However, the one thing in common is that a backup will bail you out if something goes wrong.
  
• Turn off any and all caching plugins. Caching plugins saves versions of your site to speed up loading. So the cached versions of your site have the older theme.
  
• Update plugins on your site. This step may not apply to you if you keep everything on your site regularly updated. However, you may have inherited a WordPress site that hasn’t seen an update for years, so need to proceed carefully. We advise updating plugins first, then themes, and finally updating WordPress—and that too in stages.
  
• Use a maintenance plugin. Some updates take a while and can mess with the design of the live site. To avoid a poor experience for your site visitors, install a maintenance plugin before making any changes.

Step 2: Consider theme customisations

If you have added customisations to your WordPress theme and would like not to lose them during an update, this is a good time to create a child theme.

You may not have any customisations at all—or you already have a child theme—in which cases, skip this step altogether. 

1. Go into the wp-content directory, and then into themes, on your site, using either FTP or cPanel’s File Manager. 

2. Create a folder in the themes directory, and then another folder inside it. Name this directory with the parent theme name and -child added to it. This format is not strictly necessary but it is considered best practice. So let’s stick with that. 

3. Connect the child theme to its parent. You will need to do with the functions.php and the style.css files.

4. Copy any and all customizations from the functions.php file and stylesheet (style.css) from the parent theme into the corresponding ones in the child theme. 

5. Make the child theme the active one on your site. 

Your site should look and behave exactly the same as before.

📝 Creating a child theme for customisations is considered best practice, and it is precisely to account for theme updates.

Let’s be honest: updating a WordPress theme is bad enough. Updating a WordPress theme which has customisations? Nightmare.

WordPress theme updates are crucial for security and performance, but they can feel overwhelming when you’ve invested time in customizing your site. The reality is that updating WordPress theme files without proper preparation can wipe out months of careful tweaks and modifications.

WordPress updates always carry the risk of crashing your site. But theme updates go one step further, when you risk losing all the customisation you’ve carefully added.

The good news is: there are several ways to handle this. In this comprehensive guide, we’ll show you exactly how to update a theme in WordPress without losing your custom changes, step by step. Whether you’re managing a single site or dealing with WordPress theme updates and customization across multiple projects, these methods will keep your site secure and your customizations intact.

Understanding WordPress theme updates and customisation

Before diving into the technical steps, it’s important to understand the relationship between WordPress theme updates and customisation.

Theme developers release updates to fix bugs, patch security vulnerabilities, and add new features. However, they have no way of knowing what customisations you’ve made. So when updating WordPress theme files, the system simply overwrites everything with the new version.

This is why updating themes in WordPress safely requires a strategic approach that protects your customisations while allowing you to benefit from important updates.

Step 3: Use a plugin to update a theme in WordPress [SAFELY]

The best way to update a theme is to use Sandbox updates on BlogVault.

1. Open the Site Details page, and scroll down. You’ll see a section with Plugins, Themes, and WordPress. The numbers indicate available updates. Select which theme you want to update.

2. Select Sandbox Updates. This is the safest way to update a theme. Click on Upgrade to continue. Wait for the update to run.

3. You will see a visual regression of the site before and after the update. Check to see if everything is where it should be, and if the variance is 0%. If there is the slightest variance, check it on the staging site BlogVault as created automatically. The update has not yet been applied to your live site, so don’t worry.

Step 4: Test the theme update thoroughly

After the theme has been updated, make sure to test your site thoroughly.

Although the visual regression testing on BlogVault will pick up any anomalies in design or UI, you need to also check for broken functionality in forms or buttons, and generally go through all your major pages to confirm that everything is working as it should. 

Here are the key areas to test:

Step 5: Approve the update on your live site

Once you’ve reviewed the report, and resolved any issues, you can approve the update for your live site.

And that’s it! You’ve successfully updated the theme on your WordPress site, without losing any customisations.

How to use a staging site for theme update

If you want to update your theme manually, first create a WordPress staging site. A staging site is an exact replica of your site, so you can test out updates in a safe environment without it affecting your live site at all.

If the update breaks the design or causes a critical error because of a conflict with a plugin, you can simply delete the staging site and start again. All this while your live site is live and working.

1. Install and activate BlogVault. Give your site a few minutes to sync.

2. Go to the Site Overview page. There, you will see a section for Staging. Here is where you are able to create a staging site from a site backup.

3. Wait for the staging site to be created.

4. Copy the credentials and get started. Click on Visit Staging to log into your new staging site. To log into wp-admin, use the same credentials you use to log into your live site.

5. Update the theme on your staging site. There are several ways to update your WordPress theme. For stock themes or those available on the WordPress repository, you can run the update from wp-admin. For premium or custom themes, you’ll need to get the ZIP from the developer, and upload it to your site for installation.

We have described both methods, and others as well, in full detail in the next section. You can pick the one that best suits your site, and try it out on the staging site, as per your preference.

6. Replicate the theme update on your live site. Once you’re thoroughly satisfied with the theme update on staging, replicate it on your live site.

While there is a merge feature with BlogVault staging, it is always better to redo the changes on the live site. This way, if any changes are made to your live site while you were testing, those will not be overwritten by the merge.

Other ways to update a WordPress theme

As promised, we’re including all the ways you can update a WordPress theme.

a. Manually update a WordPress theme via wp-admin

You’ll find available updates in two places on your WordPress dashboard: 

In the Updates menu, scroll down till you see the Themes sections. The themes listed here have available updates. Use the checkboxes to select the ones you want to update, and click on Update Themes to do so. 

Alternatively, go into the Themes menu on your dashboard. The themes with available updates will have a message on top saying: New version available. Update now. 

Both these updates work in exactly the same way.

You can also upload a zip file of the theme to update it. Add it to your site the same way you would install a theme.

b. How to Update a WordPress theme Manually via FTP or cPanel

You may need to update a WordPress theme manually via FTP or cPanel’s File Manager if automatic updates aren’t available for your theme. This is especially true in the case of premium and custom themes. 

We’re going to go ahead and assume that there are customizations in the theme and walk you through the steps to update your theme considering those. If your theme doesn’t have customizations, simply skip those steps. An FTP client and cPanel work in very similar ways, so we’ll use FileZilla to demonstrate the steps.

1. Download a backup of your theme files. From the BlogVault dashboard, you’ll find an option to download a backup of your site. 

Since you need only the theme files, navigate to the directory in wp-content, and use the checkbox to select the theme folder. 

Alternatively, you can use FTP to do the same thing. Log into your FTP client, and navigate to the themes folder. Right-click on the theme you want to update, and download it to your computer. This serves as a backup. 

2. Get the new theme files from the repository, or wherever else the update exists. This could be from the theme developer’s site, for instance, or a zip file sent to you by a custom theme developer. 

3. Copy over the customizations from the backup to the new version, keeping everything else intact. Generally, customizations are added to the functions.php and the style.css files. If you cannot remember the changes you have made, you can use a file comparison utility like a diff checker to find the differences.

4. Make sure to activate another theme on your site. This will avoid any issues of downtime.

5. Upload the updated theme folder to your site, in the themes folder. You may be prompted to overwrite the existing theme folder. Go ahead and do that.   

6. Finally, activate the uploaded and updated theme on your site.

c. Manually update theme using WP-CLI

Many WordPress admins prefer managing site updates via the command line, as they can perform these tasks much quicker. That being said, you would need to have WP-CLI installed on your computer, and be familiar with command-line usage to do so successfully. If this is not something that’s up your alley, we suggest skipping this section altogether. 

1. Connect to your site’s server using SSH credentials. These are often the same as the FTP credentials. 

2. Navigate to the root directory of your site, where WordPress is installed. This could be public_html or www. 

3. Use the wp theme update command to update themes.

There are a few ways to use this command, depending on which theme and how many of them you want to update in one fell swoop. 

• To update all the themes on your site: wp theme update --all 
• To update a specific theme (replace themename with the name of the theme folder): wp theme update themename
• To update multiple specific themes (replace theme1 and theme2 with the names of themes, and separate them with spaces: wp theme update theme1 theme2 
• To update all themes at once, except a certain one (replace themename with the name of the theme folder): wp theme update --all --exclude=themename

d. Scheduled and automatic theme updates

Automatic theme updates with BlogVault are especially useful, because you can set them on a schedule. Additionally, you can update the theme across multiple sites in one operation, and only receive update emails. The best part is that before each update, BlogVault takes an automatic backup of your entire site. So even if something is wrong with the update, you can restore your site immediately. 

It is super simple to set up a schedule. 

1. Go into your BlogVault dashboard, and go into the Site Details page. 

2. Scroll down, and on the left side you should see a section to set up Auto Updates. Click on Schedule to set one up. 

3. Name the schedule something meaningful, so you can identify it easily later. Pick a cadence, and finally select the themes you want to update automatically. We picked the WordPress stock themes on 4 test sites. 

Make sure to check the backup and the visual regression test boxes. Finally, click on Create. 

On the next screen, you will be able to see all the schedules you have created. Every time the schedule runs, you’ll get an email with the results. If the update fails, you can rest assured that there’s a backup readily available to restore your site in minutes.

e. Enable WordPress auto-updates for themes

WordPress launched the auto update feature in version 5.5 and included plugins and themes in addition to WordPress updates. If you are feeling confident that a theme update will not break your site, or have daily backups enabled, you can think about this as an option.

There are many considerations that go into managing auto-updates for themes (and plugins for good measure), so we advise caution when choosing this option.

Whichever method you choose, please make sure to take a backup of your site. Even official updates from theme developers can have inadvertent issues that can cause a site to crash.

How to choose the right update method

Spoilt for choice? Here is a handy guide on choosing the right method to update the theme on your site.

There are two main factors:

Types of themes

The type of theme on your site will determine whether updates are available and what methods you can use to update them. There are 3 types of themes: 

Different types of theme customisation

Once you’ve figured out the type of theme, you can shortlist which methods can be used to update it; which method you should choose depends on theme customisation.  

As we know, a WordPress theme controls the aesthetics of a site: design, font, colours, etc. Themes are intended to be largely interchangeable, so WordPress advises functionality is best left to plugins.

However, that doesn’t stop many designers, developers, and even site admin adding special functionality to a theme, either by adding it to the functions.php file or bundling it into a companion plugin. Now you know why updating a page builder is such a pain.

Depending on who has added the extra functionality to the theme—the developer or the site admin—it can impact the update process. If the theme developer does it, the functionality is considered a core part of the theme, and is unlikely to be overwritten or lost during an update. However, when anyone else makes a change to the theme files, these are known as customisations which can be lost during an update.

Customisation affects the time it takes to update a WordPress theme as well.  

Editing the code in theme files

Perhaps you or your site developer has modified the theme files, and are now afraid that an update will wipe it out. This is a valid fear, because anything not included by the theme developer will be wiped out regardless of how critical it is to your site. 

For example, consider tracking pixels and other code snippets required by analytics tools. According to most integration instructions, the tool developers will recommend adding it to every page on your site. On WordPress, the easiest way to do that is to add it to the theme’s header.php file. There are a plethora of plugins that can add the code to your header.php file, but you can choose to do so directly. In the latter case, if you were to update the theme, this code would get wiped out during the update. 

This is an example of a relatively small addition, so it can feel insignificant. However, many site admin and their designers can add a lot of functionality in the same way. Similar changes can be made to the theme stylesheet, the style.css file. 

If you have edited the code, you will need to save changes elsewhere and then copy them back into the updated theme.

In-theme customisations using theme customiser or editor

Themes are meant to templatise WordPress site design, so that the aesthetics are in place. However, you will still need to tweak certain elements to customise them to your site, especially if you’re activating the theme on a brand new site. 

For instance, you will want to change the site’s title, assuming you haven’t already done so from the General settings on wp-admin. Or perhaps you are changing the colour scheme (something you cannot do from General settings).

On older versions of WordPress, you would use the Customise option under the Appearance menu. After WordPress 6.0, you would use the Editor option. 

These customisations are options that you have changed from their defaults to suit your website. In most cases, these options are stored in the site database, which is totally unaffected by a theme update. 

Page builder customisations 

You can use page builder plugins to make changes to your site design as well. You can add and remove custom blocks, change the layout of pages, and import new templates altogether. 

Page builders don’t so much make changes to your theme, as interact with them to change the design. The changes are controlled by the plugins, which are unaffected by theme updates. 

🚨 Page builder changes, like Elementor updates, are a completely different beast, and shouldn’t be confused with theme updates.

Changes made via a child theme

A child theme is a WordPress theme that inherits its features, functionality, and styling from another theme, called a parent theme. Child themes are used to customise themes, by making changes to theme files. These changes are safe during updates, as the parent theme’s files are overwritten, and the child theme’s files are not. The child benefits from the update as well, as it is connected to the parent theme. 

WordPress always recommends using child themes for customisation as far as possible. In the staging method of theme updates below, we will link to resources of creating a child theme as well. 

🚨 In essence, any change made directly to a theme file is under threat of being wiped out, unless you are using a child theme. Any changes made via plugins (even page builders) are safe from deletion.

When to use different methods for updating WordPress theme

Choosing how to update themes in WordPress depends on several factors. Here’s a quick decision guide:

👉 Use sandbox updates when:

• You’re new to WordPress theme updates
• Your site has complex customisations
• You manage client websites professionally
• You want maximum safety with minimal effort

👉 Use staging sites when:

• You need extended testing time
• You’re dealing with WordPress theme updates and customisation that require thorough review
• You want to test multiple changes simultaneously

👉 Use manual updates when:

• Working with premium themes
• Automatic updates aren’t available
• You need granular control over the process

👉 Use scheduled updates when:

• Managing multiple sites
• You want WordPress theme updates to happen automatically
• You have reliable backup systems in place

Extra considerations when updating a theme on a multisite network

We have tested the methods above on multisite networks as well, and our only observation is that they are applicable from the network dashboard only. Subsites in our experience will not have the option to update any themes directly. 

Best practices for updating a WordPress theme

Any change to your site is fraught with worry, even if they are wholesome and necessary changes like updates. Here are a few tips to get you through the stress as unscathed as possible. 

Troubleshooting: what if something goes wrong with a theme update and how to fix it

Theme updates can also fail. In spite of all precautions, sometimes Murphy’s Law wins the day.

Here are a few ways to troubleshoot commonly faced issues during a theme update. 

• Can’t see update notifications on wp-admin. There are a few things that can be the issue here:
  • You need to be using WordPress 5.5 and above to see auto update links in the Theme Details section. If you are using an older version of WordPress, please consider updating on priority, because a theme update is not remotely the biggest problem you are currently facing. 
  • Keep in mind that if you are using a premium, third party, or custom theme, you may not see update notifications. Good developers like Divi or Themeforest will show notifications—even if you cannot update directly from wp-admin—but it is not necessarily a given for any premium theme. 
  • For a custom theme, you would then need to contact the theme developer to request updates.
• Can’t update a premium theme on a staging site. This may be because of how licences work. Some premium themes require a licence per installation. In this situation, you can try writing into their support to see if they will make an exemption for staging sites. Otherwise you may need to forego staging altogether and use backups for insurance. Fingers crossed.
• Site crashes after theme update. This is why you used staging in the first place. Enable wp-debug on your staging site to figure out what has caused the issue. Perhaps there is a conflict with a plugin, in which case you need to figure out which plugin. Disable the lot and re-enable again one at a time to find the culprit. Alternatively the update didn’t go as planned. Restore a backup and start again. If you didn’t use staging, hopefully you took a backup. Restore that, and this time around use staging.  
• An update changes something in the parent theme that breaks the way a child theme works. Troubleshooting this is a little more technical, as it involves understanding how the code in the child theme interacts with the parent theme, and why it is causing the issue. In this case, involve a developer and reach out to the theme developers for help. 
• “Something went wrong. Your change may not have been saved. Please try again. There is also a chance that you may need to manually fix and upload the file over FTP.” If you encounter this error while using the WordPress theme editor to replace code customisations, there could be a bunch of things going wrong. This error was introduced into WordPress in version 4.9, and has since been resolved. If you are using such an outdated version of WordPress, this is the main problem. You need to update WordPress immediately. If that’s not possible for any reason, try updating the file you’re editing manually, and upload to your site via FTP. 

You may have to rollback a theme update, if none of these troubleshooting steps work. After that, contact the developer.

As a general rule of thumb, anything that goes wrong with a theme update after you have taken the requisite precautions of a staging site and backups, fall within the purview of the theme developer. Support is a major perk of purchasing and using a premium theme, so you should absolutely use the facility.

Conclusion

There are several ways to update a WordPress theme. The safest and best way is to use sandbox updates with BlogVault. With the automatically created staging, visual regression testing, and then the approval to go live on your site, BlogVault Sandbox updates make any theme update an absolute breeze.

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