Designing for the edge cases

A common mistake is to only plan for the perfect scenario. Great designs prepare for the unexpected, as well as the ideal.

If my career as UX designer has taught me anything, it’s that people rarely use your products the way you expect.

Usability issues are most likely to happen when the unexpected occurs.

When edge cases pop up, it’s make-or-break time for your website or app’s design. If you haven’t planned how the interface will deal with unusual scenarios, the whole experience can quickly fall down.

A frequent mistake I see time and again is designers only planning for the best possible scenario. After all, the ‘ideal world’ versions of your layouts are the ones used in presentations. They’re the ones that clients look at for design approval. They’re the ones you’ll be putting in your portfolio.

In reality, designing for the less-than-desirable situations is just as important.

Why plan for the unexpected?

Let’s say you’ve sent some approved designs to a developer. That developer might find possible scenarios (an error, for example) that haven’t been thought about in the design.

If that developer doesn’t have designs for these states, they’ll be forced to make assumptions about how the system behaves. The developer won’t necessarily have the time or the knowledge to come up with the best possible solution by themselves. This is how usability issues find their way in a product.

I’m going to share some edge case scenarios you might have to deal with, and how you can plan for them in your designs.

Error states

Whenever some kind of interaction is takes place, there will usually be the possibility for an error. This is particularly true when the user needs to provide input. A checkout form would be a good example of this.

It’s true that the best way to handle errors is to prevent them happening in the first place. That said, we still need to cover every scenario. It’s almost certain that your system will be capable of some type of error, and these need to be planned for during the design phase.

There are many different kinds of errors…

  • Validation - The user didn’t enter information in the way the system needed.
  • Submission - There was a technical error that wasn’t the user fault.
  • Content - The user requested something we can’t give them.

When designing your product, identify every scenario in which an error could occur. You can then design a state for it, and ensure the system is handling that error gracefully. This can be time consuming, but it’s the attention to detail that really benefits the experience.

There are a few different things to think about here…

  • How the error appears - We should use animation or contrast to draw the user’s attention.
  • Styling and position - The error notification should be visually linked to where the problem took place.
  • Language - Errors should be written in a clear, user-friendly and on-brand way. Avoid ‘tech speak’ at all costs.
  • Clear solutions - After informing the user of an error, we should also allude to a solution. This might be an instruction, or a link to something else that might help.

Screenshot of Apple's user friendly login screen. It presents error messages in a userful way.

The login screen for iOS handles incorrect passwords really nicely. After entering an incorrect password, the field does a little shake from side-to-side (like someone shaking their head). This draws the user’s attention to the source of the problem. The clear text makes sure the user understands the problem. The field also indicates when caps-lock is turned on, addressing another common issue.

Screenshot of user friendly errors in Asos' checkout form.

Asos work really hard to refine and optimise their checkout form. Error messages display in-line as soon as a mistake is made, in a really obvious way. The messages themselves are meticulously tested and worded, so it’s crystal clear what has gone wrong.

Screenshot of AirBnb's user friendly 404 error page.

404’s are an error that can happen on almost any website. A 404 occurs if the user is linked to a page that doesn’t exist. Air BnB handles this in a great way. It explains the problem clearly without using any ’tech speak’. It also adds a little humour, which can go a long way to easing the user’s frustration. It’s then got some suggested links, so the user isn’t stuck for what to do next.

‘0 results found’

Most content-rich sites will need some kind of search feature. This is especially important for ecommerce, where the user’s ability to find a product can directly affect profits.

‘0 results found’ is one of the most common usability issues I’ve seen across all the sites I’ve ever worked on. Given this, I find it astounding how often they’re not planned for by the UX designer.

If you’re designing a site that has free text search, you really must give consideration to what happens when it doesn’t return any results.

You might want to think about :

  • Language & visuals - Explain what went wrong in a clear and helpful way. Once again we need to avoid ‘tech speak’.
  • Suggestions - Provide some alternative search terms, or a spell-check. If you can’t do this due to technology restrictions, then just having links to popular searches can be better than nothing.
  • Featured content - If you don’t have what the user is looking for, then perhaps you can promote the next best thing instead. Featuring something really interesting or new (even if it’s unrelated to the search) might be enough to prevent the user from leaving.
  • Contact information - Give the user a way of reaching you. Perhaps the something they’re looking for needs to be added, or maybe they could speak to someone who can help them?

Screenshot of amazon's 0 results found page. It presents the user with useful information.

Amazon provide a great example of a ‘0 results found’ page done right. They give suggestions for further searching, in addition to promoting some other related products. If all else fails, there’s also a clear feedback form.

Empty states

It’s possible that certain screens in your site or app that usually show content might have nothing to display at certain times.

For example, an app with an activity feed may have nothing to show if the user hasn’t started using it yet. We need to think about how the page looks in this case.

In the absence of content, don’t just show empty space. Instead, the design should make it clear what would normally be shown. We can also use this space to give clear instructions on how to get started.

This doesn’t just apply for apps, either.

if we were designing a site an ‘upcoming events’ section on a website, we’d need to design how it looks if there were no events planned. Rather than just showing an empty space, we’d want to tell the user when to expect new events - providing any other useful links or information. You might even want them to sign up for notifications when events do become available.

Screenshot of empty states in various apps.

The Tumblr app shows me an empty state the first time I see my dashboard. If I haven’t started following any blogs yet created yet, I get a nice illustration telling me what to normally expect here.

The same is true for most well designed native apps. In place of content, you’ll see a prominent call to action on how you can get started.

Tutorials & onboarding

Beyond the empty state, giving the user instructions on how to get started can be really helpful.

A tutorial can be a great way to ease people into your app’s features. Using subtle animation or prompts within the normal user interface can get the user started on some key tasks.

The best tutorials are unobtrusive. Rather than showing an overlong video or slideshow of instructions, putting prompts in the context of the experience itself can be really effective. This helps the user learn by doing, rather than having to take in loads of information passively.

Note that tutorials should only be used if really necessary.

If your interface is self-explanatory, it might not be relevant. Whether or not to include a tutorial is a design consideration you need to make.

Screenshot of tutorials in various apps.

These great examples from Feedly and Bechance show how tutorials can be built into the app experience. They help the user to understand the app’s features, whilst getting them started actually using it.

Unpredictable content

We tend to create mock-ups with an ‘ideal world’ view of the site’s content. Copy is usually just the right length. Images are selected perfectly. We go to lengths avoiding widows or ugly wrapping in the text.

Once the reigns of a content management system are handed over to the content team, these things can’t be guaranteed.

For example, if we design a page expecting to give the user four different choices, what happens if there ends up being forty? How does that display? Do we start using pagination? Some sort of lazy-loading? Planning for this sort of thing can help prevent issues later.

The length of copy can also affect the design in a big way.

When using labels or names in your UI, make sure to test with extra long examples. If we’re designing an app that needs to display the user’s name, that needs to work for longer names too. If you’ve only been designing for “James Smith”, will the system cope if “Hubert Blaine Wolfeschlegelsteinhausenbergerdorff” uses it?

The same goes for languages. If there’s any possibility your experience might be translated, you need to make sure the design can support it. I like to use German as a ’test translation’. Words tend to be much longer, and can reveal issues with navigation not having enough space. Your content experience might need to work in a right-to-left format for asian and arabic markets. The earlier you identify these kinds of challenges, the sooner you can find solutions for them.

Design for every eventuality

Good design is all about attention to detail. It’s this commitment to designing for every scenario that set great experiences apart from average ones.

Make it your responsibility as a designer to plan for these edge cases. They’ll happen whether you design for them or not, so it’s best to be prepared!

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Chris Myhill, an incredibly handsome UX designer who heads up Just UX Design

Chris Myhill

Chris heads up Just UX Design with 10 years of experience creating digital products and managing design teams.

He’s worked on loads of different projects, using UX wizardry to help businesses make better products.

Learn more about Chris

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