How to Upgrade a WordPress Theme — Even if It’s Customized

There are a number of different ways to upgrade a WordPress theme depending on your specific situation. This post will go over some of the most common, including upgrading themes that you have customized.

Of course you should backup your database and your current theme before you proceed with any method in case something goes wrong.

The Automatic Upgrade

The automatic upgrade is, of course, the easiest. But it’s also one of the least common.

If you are using a default WordPress theme like Twenty Ten or Twenty Eleven, then you’re no doubt familiar with the easy, one-click upgrades. Some premium themes are also beginning to offer the automatic, one-click upgrade, but many still do not.

The automatic upgrade is as easy as it sounds. Simply click a button, and you’re done.

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Uploading a New Theme

At the present time, most themes you use will still require uploading a new version of the theme in order to upgrade it. If you attempt to upload a new version of a theme that is already on your server through the theme section in the admin area, it will fail, and you will get a message that looks like this.

Two Easy Solutions

1.  One easy solution is to simply delete the old theme first, and then upload the new theme. (Make sure you have a copy of your old theme on your computer in case something goes wrong with the new theme.)

2.  If deleting a theme makes your nervous, then another option is to rename the newer version while it’s still on your computer, and then upload it.

In order to rename the newer version, follow these step:

  1. Unzip the newer version on your computer
  2. Once unzipped, open the folder, and you should find another folder.
  3. Rename this inside folder. You can just add “new” to it (e.g. “mytheme-new”).
  4. Copy or move this newly renamed folder OUT of the other folder it was in.
  5. Once you have your newly renamed folder out of the old folder and by itself, zip it.
  6. Upload this newly renamed folder via the theme section in your admin area.

When you follow this second method, you should now see two themes with the same name but with different version numbers.

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Upgrading a Theme that’s been Customized

Uploading Only Changed Files

If you’ve customized your theme, then the first thing you may want to do is see if the changes to the new version of your theme are extensive or not.

If your theme’s author has provided you with a list of changes in the new version, and only a file or two has been changed, you may opt to just upload and overwrite the files in the older version via the ftp function on your server of an ftp client.

If any of those files happened to be ones you’ve customized, then just go back in and customize them again after you’ve uploaded the new versions.

(Note: Your theme may have a “changelog” file in it that will tell you the changes in the newest version. If not there, it may be in the “readme” file. If not there, it may be on your theme author’s website.)

Re-customizing Your New Theme

For some people, however, the only answer will be to re-customize your upgraded theme. You can either do this on your computer and then upload it to your server. Or you can upload it to your server and then re-customize it there.

In either case, I would suggest using the basic renaming method outlined in option #2 above in “Two Easy Solutions.

In other words, leave your currently modified theme on your server/site as it is, and then rename a copy of the newly upgraded version and modify that to match your current customizations. When you finished modifying it, upload it so that you have both the new version and the old version on your server at the same time. In this way, if something has gone wrong with the new version, you’re just a few clicks away from getting things back to where they were.

Also, if you are going to be modifying the new theme, then I would also suggest making a copy of it before you start modifying it so that you always have an clean copy at hand.

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What If I Can’t Remember My Customizations?

If you can’t remember what customizations you’ve made, there’s still hope. It may be a lot more work, but there’s still hope.

There are programs you can get that will let you compare two versions of your theme (your old version vs. your old customized version, for example … or your old customized version to your new upgrade version).

If you use a PC, WinMerge is a free program that will help you to do this. Kaleidoscope (not free) is a similar program for Mac.

A quick example of WinMerge will give you an idea of how it works.

You upload your two themes into the program – one on the left-hand side and one on the right-hand side.

At first you see only one list of files. The ones in red are files that are different in the two different themes.

Clicking on a file will open the file in the two different themes side-by-side.

You then have a number of different options to navigate to the differences and change them if you like. For example, you can make a line in the left-hand version the same as its counterpart in the right-hand version or vice versa. You can also change the entire files in a similar way.

Make Copies, Make Backups

Regardless of your situation, as mentioned before, just make sure you make backups of everything – database, new theme, old theme, etc. Keep originals of your current theme and your new theme in a safe place. Then make copies and go crazy.

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Photo: Browse The Upgrade – Orange from BigStock

Comments (24)

  1. This is a great article. Thanks for the insight.

    I also use a free plugin from iThemes called Easy Theme and Plugin Upgrades to protect against accidental overwrites.

    This plugin adjusts the upgrade process for themes and plugins and adds a step that zips up the current theme/plugin and puts it in the uploads area before it unpacks the new update. That way if something screws up, you always have a backup of what was there before.

    Thanks again for a great article. This one’s straight to Evernote for me.

    • Thanks, Nathan. I actually tested that plugin out with the hopes of including it in the post, but it wasn’t working for me, so I had to leave it out. Hopefully iThemes will get any bugs worked out. I like the idea of the plugin.

  2. For upgrades of important things like themes and my primary plugins, I SSH into the server, rename the theme folder or plugin folder by adding a dot in front of it, then use wget to pull the new theme or plugin archive to the server. A quick unzip, then you can use diff to compare the “dotted” folder with the new folder. I know it’s a manual way of doing it, but after losing customizations more than once, I prefer this hands-on way of upgrading.

      • Thank you. This article is very informative, however, when I upload my WP theme files (as ZIP files) to WinMerge, I get a garbled mess of what looks like wingdings, such as below. I am not seeing any clean list of files to compare. I’m not finding a solution through WinMerge documentation and am just wondering if you or anyone else has ever experienced this. I’m nervous about updating my theme as we created some entirely new pages. Thank you in advance.


        • Hi Glenn – I’m not sure of the answer to this, but asked others, and even though they weren’t sure either, here were their guesses:

          - could be wrong character encoding setting in the program or could be obfuscated code in the theme

          - If we take the “(as ZIP files)” note literally, could it be because WinMerge doesn’t deal so well with binary files

  3. Thank you so much for sharing this tutorial.
    I hope this one will work for me. I will get back to you if I have some question. Great article!


  4. Thank you for writing up this thorough walkthrough! :)

    I have a question though. Is the indicator that asks you to update the theme supposed to go away if done correctly? My dashboard still says there is a new update available.

    • Garo — I think the indicator would go away. That warning might be stuck in your cache. Just keep refreshing (hit your F5 key) and see if that does it. You could also check in another browser. If it still hasn’t gone away, you might ask the theme creator about it.