How To Customize Your Error Pages: A Beginner Web Dev Project (Part 1: Back-End Basics)

I came across one of my Error Pages and noticed it was missing images and looked bad. They’re fun to customize, and a great 1st-time web developer project. I’ll show you how!

Here’s how to customize your Error Pages–if you have a cPanel hosting interface. Or learn how to code it here, then figure how to deploy it on your non-cPanel hosting account.

Over the course of writing this, it turned into a Beginner’s Intro to Responsive and Accessible HTML & CSS tutorial, so read on if you’re interested in that.

Let’s start with cPanel. Where are your cPanel Error Pages?

First, login to cPanel. It’s in your hosting account when you login, you’ll see something like “Manage your Hosting Account” or “Go to cPanel“. You may not have cPanel as your hosting server admin. You may have a Windows IIS hosting account, or a different admin OS. Even if you don’t have cPanel, the basic HTML & CSS tutorial below still works.

Create or Update 404 Error Pages - cPanel - find Error Pages 0 — Create or Update 404 Error Pages – cPanel – find Error Pages 0

In the Admin Panel, scroll down to the “Advanced” card. Select “Error Pages”.

cPanel Custom Error Pages: Step 1

Select which domain you’re editing error pages for (in case you have multiple domains on this hosting account). I chose krisbunda.com for this exercise.

cPanel Custom Error Pages: Step 2

Select which type of error page you want to edit. I chose 404 for this example (and I plan on making code that can be pasted into all the other error types’ pages).

Create or Update 404 Error Pages - cPanel - find Error Pages 1 — Create or Update 404 Error Pages – cPanel – find Error Pages 1

Here’s where you paste your HTML / CSS / JS / etc. for this error page. I edit the code in Visual Studio Code and paste it back here when I want to view it live. It gets tedious, but ever since I started using Cloudflare for this site’s nameservers, it’s made the traditional web development method of uploading code via FTP difficult.

Notice it is a file named “404.shtml”. The S in SHTML stands for “Server”.
Also notice the little “Select Tags to Insert” section, with an array of server-side include tags you can add to the page. These are good for making this code reusable, and something that can be pasted into the other error pages with minimal or no changes.

Create or Update 404 Error Pages - cPanel - find Error Pages 2 — Create or Update 404 Error Pages – cPanel – find Error Pages 2

See what the code looked like before–notice the  part. That’s a SSI, and it shows in the error page as the URL that triggered the serving of the error page. I know that sounds circular, sorry. On the page, it reads like krisbunda.com/ Here's the NONEXISTENT FILE URL you entered, no matter what that nonexistent file URL is.

Create or Update 404 Error Pages - cPanel - shtml code - Before — Create or Update 404 Error Pages – cPanel – shtml code – Before

Upload Images (Optional)

If you’re making custom error pages, you probably want to put an image or two on it. I’m going to put three:

a Kris Bunda Design logo SVG at the top,
a cartoon eyes animated GIF that’s supposed to be “looking” for the missing file that brought the user to the error page,
and I’ll put another branded animation at the bottom, because I like it.

LOGO Kris Bunda Design SVG

Pixel-Perfect Design by Kris Bunda - animated GIF — Pixel-Perfect Design by Kris Bunda – animated GIF

I uploaded image files via the File Explorer utility in the cPanel admin panel:

In cPanel, scroll to the “Files” card, choose “File Manager”.

Create or Update 404 Error Pages - cPanel - File Manager — Create or Update 404 Error Pages – cPanel – File Manager

Know where your files live.

Wherever you upload your photos, just know their URL addresses so you can make them show up in your custom error pages, i.e., <img src="/theURLofThisImage.JPG">.

It’s assumed you know how a computer file system works, which is how a URL works. Forward slashes are usually folders, the text in between slashes are folder or file names. I saved my image files to a folder named “img” at the “root” of my domain (krisbunda.com). This means you should be able to go to krisbunda.com/img/EYES.gif and see the eyes animation. Remember, spelling and even case is important. If I type krisbunda.com/img/eyes.gif, it’s likely to show the 404 error page because it “can not locate” a file named lower-case “eyes.gif” at that location. Some schema allow forgiveness and servers will look for different cases or files without the correct extension spellings, but don’t count on it.

Create or Update 404 Error Pages - upload new images to site 1 — Create or Update 404 Error Pages – upload new images to site 1

CSS: Inline Styling

I know inline CSS is supposed to be grounds for a tar and feathering. But I started typing in some styling since this is a simple page and I wanted to get started. We can refactor out the glaring inefficiencies later (like styling multiple HTML elements the same way instead of just giving them a class and styling the class one time in the head of the document).

Elements and Styling them

Wrapper <div>, background-color, font-family

I made an overall “wrapper” <div> as the first div inside the <body> tag. It’s going to set some style rules for other elements inside it. (Child elements will inherit some styles from their “parent” container, or in other words: some styles will “cascade” onto them [CSS stands for Cascading Style Sheets ])

The wrapper <div> has an aqua background-color and Arial font family (or any sans-serif fall-back choice of the device if the user doesn’t have that font installed).

Create or Update 404 Error Pages - cPanel - shtml code redo - wrapper div — Create or Update 404 Error Pages – cPanel – shtml code redo – wrapper div

Element Styling and Hyperlinking

<img> size & max-width, and image-as-link <a href>

I want the logo image to link to the home page (all the images do).

Link text is “anchor text,” which is where the “a” comes in.
href stands for hyperlink reference.
E.g.: <a href="/some-url">Text you see on webpage</a>.
And that’s going to look like this on the rendered page: Text you see on webpage.

I want the logo image to be 500 pixels wide if it has the room, or 80% the width of its parent container if less room.

Images are placed using an <img> tag with src="/some-url" syntax. I’ve added inline styling to this image element tag using style="" syntax.

<img style="width: 500px; max-width: 80%; margin: 5px 0;" src="/img/LOGO Kris Bunda Design SVG.svg">

Styling “Responsive Behavior”

Image Size: In this example, the image should display at 500 pixels wide, or no larger than 80% the width of the <div> container it’s in.

animation showing header logo styled to be 500 pixels wide or no wider than 80% of parent container’s width.

Responsive Design: Being able to have elements scale up and down gracefully, so as not to display ridiculously large or small regardless of screen size or orientation, is a tenet of “Responsive Design”. You can go to krisbunda.com/x and shrink the width of your browser to see this in action (or look at the GIF animation above).

Margin: I also styled the image to have a top and bottom margin (invisible spacer) of 5 pixels, and side margins of 0px, or: style="margin: 5px 0". You’ll get to know “shorthand” tricks like this if you keep learning CSS. The non-shorthand version would be: style="margin: 5px 0 5 0". I think of div border attributes as the cardinal compass points, starting with North (Top Margin, 5px wide) and going clockwise through East (Right Margin, 0px wide), and so on. Just remember: Start at Top, Go clockwise.

Where’s the file? Image Source. <img src=”/some.png”>

I know we touched on this above, with hyperlinking an image, styling an image, and knowing the URL address of your image, which is its “src”… So let’s bring it on home again by telling the server where your files are located (their URLs or sources), and then let’s put it all together, source, link, and styling.

The <img> tag must also show where the image file is located using source syntax, as in: <img src="https://your_site.net/photo_name.jpg">

Finally, here’s what the whole `<img>` tag wrapped in an `<a>` tag (anchor or hyperlink) might look like:

<a href="/">
<img style="width: 500px; max-width: 80%; margin: 5px 0;" src="/img/LOGO Kris Bunda Design SVG.svg">
</a>

Note there are 4 important parts here:

The link element
The image element (nested inside the link element)
Style attributes (inside the image element)
Source attribute (inside the image element)

Why the <a href=“/”>Forward Slash?</a>

Why does the <a href="/"> tag just have a forward slash ("/") for the hyperlink address? Because that should take the user to the homepage at the root of the domain. In other words, to the very top-level of the file system for the domain. The domain in this tutorial is krisbunda.com . The forward slash is like a shorthand, and takes the user to krisbunda.com/. See that forward slash at the end of the domain?

(Not to confuse you, but I have my domain to forwarded to /blog. So even though <a href="/"> sends you to krisbunda.com/, you’ll then be auto-forwarded to krisbunda.com/blog/, which is the folder my wordpress installation resides in, and therefore you will load the homepage of my wordpress installation, which I set to a summary list of my blogs.)

Notice the 2 Server-Side Includes in the code!

One for REDIRECT_STATUS and one for REQUEST_URI.

Create or Update 404 Error Pages - cPanel - shtml code redo - Server Side Includes — Create or Update 404 Error Pages – cPanel – shtml code redo – Server Side Includes

“Error Number” SSI Code

REDIRECT_STATUS is responsible for the “404” in the <H1> headline title “That's a 404 Error.” Why? Because then I can paste that code in all error pages, and they’ll all correctly say “That's a [correct code number; like 400, 500, 403, etc.] Error.” One of the tenets of programming is “DRY: Don’t Repeat Yourself“. If I can reuse the code we write for the 404 error page on all the other pages, then let’s do it.

“Error URL” SSI Code

The REQUEST_URI SSI code will inject the URL (without domain) of the file path that triggered serving the error page to the user. I like using this because it tells the user exactly which URL is probably no longer available to them, so hopefully there’s no confusion. The message I added says “You were looking for krisbunda.com/some URL and we're not seeing it anywhere.” Honestly, I don’t see why this isn’t reusable for most other error pages also. That’s my goal, one page of markup/styling, reused on all error pages.

Create or Update 404 Error Pages - cPanel - shtml code redo1 — Create or Update 404 Error Pages – cPanel – shtml code redo1

How we’re looking so far... I’ve got:

a text editor/IDE on the left (Visual Studio Code),
the error page in the middle,
and the Chrome “Dev Tools” panel on the right,
- Dev Tools helps me inspect elements of the site and styling I’m creating (and figure out why when something looks an unexpected way.)

That’s Part 1: Backend Basics

I’m noticing this is getting very lengthy. This looks like a good spot to end a Part 1 of this “Customize Your Error Pages while Learning Beginner Web Dev” blog, which now looks to have been about Backend Basics (getting into cPanel, uploading assets, learning about SSIs).

Part 2 will be published shortly, and will get more into Basic HTML & CSS. Probably touch on cross-browser and cross-platform testing to see if the User Experience you’re trying to present is consistent for most users. On that note, let’s show how CSS Preprocessors work to help you on that regard.

Part 3 will be after that, with a focus on Responsive Design, like Flex Box, Grid, and Viewport Breakpoints. Oh, and creating various sizes of visual assets for browsers to serve to people who don’t want to burn their data plan on 8K RETINA EVERYTHING.

Part 4 will be simply Refactoring, or rewriting code to make it neater, more DRY (Don’t Repeat Yourself), and maybe add some notes in for Future You who discovers shamefully outdated error pages and wonders what Past You was even thinking.