The worst one I've encountered is when a page says 'Field X must be entered' and then (because of a postback) it deletes everything I had written in the form. Or similar to that, going back to a page after accidentally navigating away erases all data I had saved in the form.

Very Irritating.

The worst web usability error, worst because it's so easy to fix and yet so prevalent, is not using a label element with form elements. The consequence of not using a label element is having to click tiny checkboxes, radio boxes, and input boxes instead of the text label next to them to toggle/select.

1. Click-through pages
2. Background music (which of the 25 tabs I have open is creating that noise!)
3. Most instances Flash (apart from video)
4. You need to "register" to perform even the simplest task
5. Most "call to action" images
6. 10pt or smaller font-size
7. 3rd party analytics code/adverts that take an age to download
8. Using red and green alone to distinguish between things (leaving most colorblind users cold)
9. Using images that infer more meaning than they actually should
10. Overly complicated forms with a hundred fields and drop downs
11. Useful links pages (so 1997)
12. Unexpected postbacks
13. Most instances of opening a new browser window
14. Checkboxes where its not obvious whether a check is a positive or a negative indication

...and the biggest usability error of all, that most sites are guilty of, is presenting WAY too much information on each page.

Telephone number fields that are too stupid to filter non-numeric characters, instead insisting on the One True Way to express a phone number.

That is, user enters phone number 512-555-1212, or 5125551212. The page pops up an error alert "PHONE NUMBER MUST BE ENTERED AS (NNN) NNN-NNNN".

You'd think any programmer worth at least minimum wage could do better!

Qwest's main login form "checks" the password to make sure it's "valid" without actually submitting the form to the server. Before it allows the form to be submitted, it makes sure the username and password fields consist of the "allowed" set of characters. Once those checks pass, the form is submitted to the server, where the username and password are really checked.

The problem is that the client-side script that checks the password doesn't have the correct password rules. The script thinks certain characters are disallowed when they're really perfectly fine.

I know certain characters are perfectly fine because my password includes some of them! The initial signup pages didn't check password validity, so I had no idea that the password I chose would later bring me this trouble. Thus, Qwest rejects my login without any network traffic at all. And customer support isn't helpful, either, because customer support isn't set up for accepting bug reports from people who actually know what they're talking about.

There's another login form elsewhere on the site that doesn't use the script, but it always takes me a while to find it. Instead, I've taken to using FireBug to set a breakpoint after it's checked my password, and then toggle the flag to let it consider my password as valid.

For the love of all that is holy, I cannot stand sites that cannot intuitively handle dates. Many travel sites will balk if you only enter "mm/dd" instead of just making a reasonable assumption about the year. Likewise, some sites insist that you must enter leading zeroes, or force you to use individual dropdowns to build a date.

Not accepting correct email addresses. This is especially notorious with '+' in the address. Commercial sites have lost my business because of that.

I wouldn't call this the worst, but it has the potential to be up there.

You can find this "error" on Gmail and many other sites right now including stackoverflow in this very field.

Scenario: You have a rich text editor that has most of the features of MS word. Ctrl-B makes it bold, Ctrl-I italics, etc. etc.

But what happens when you hit "tab"? You don't indent. You leave the text field and almost always land on the the submit button. So if you ever hit tab, expecting to indent and then maybe enter to add some vertical space (or you thumb hits the space bar), you just submitted the form!

I know it's rare, and it is technically the expected default behavior. Tab leaves a form input. Enter (or space) on a submit button submits.

However, there must be a better model now that we insist that are text areas behave in every other way like a text editor.

Otherwise, you may accidentally embarrass yourself in writing a quick email. Ask me how I know. ;)

Possible solutions: change the default tab order or confirm a submit on an immediate tab-space or tab-enter.

(1) Automatically-initiated audio.
(2) Some idiot javascript jockey who thinks he knows what constitutes a valid email address preventing me from using my actual email address to fill-out a web form.
(3) Registration required to use the site.

Splash pages. If I choose to load a webpage isn't it obvious that I actually want to enter?

Sites that resize your browser

Jeez I hate this one, especially now in the age of tabbed browsing, drives me nuts.

1. Javascript sites that don't work with firefox.

2. Form boxes for phone numbers or SSN's which automatically take you to the next box. For example, when the phone number is split into 3, 3, and 4. And it's almost impossible to go back to a previous box.

I absolutely hate sites that only allow for navigation triggered by hover effects. Obviously it breaks accessibility guidelines, but it also renders such a site unusable via touch-screen devices like the iPhone where hovering isn't an option.

one of the biggest fail:

target="_blank"

You shouldn't choose for user.. On my personal blog i open ALL links (no matter if is insite or external) in the same window. If an user wants new window, just ctrl click/middle click on a link. Pretty simple, heh? Is very annoying (at leas for me, dunno for you) to enter on a site and links just open in new window/tab.

Forcing users to 'page' to continue reading articles when there is absolutely no need for it. Ex: News articles / blogs blatantly seeking to increase their page hit count.

Also binding a website to a proprietary format. Ex: Netflix will not play videos on an operating system running Linux since it uses Silverlight and even tho there are Silverlight plugins for Firefox, they won't run on Firefox w/ Linux.

Long web forms, when you fill them out, your session has expired and the data is gone. You have to start over.

This must be one of the most frustrating things ever. I rarely will fill the form out again.

To me the biggest usability issue is intrusive sound. I immediately leave any website that generates, either directly or by my accidental passing of the mouse, any forms of sound, especially if via video playback. This includes ads, of course, but is common also in websites like ESPN. If I am logging on to see the headlines and my connection is slow, I don't want an automatically-starting video with this week's action.

A second usability issue for me is a news article in a website that is essentially focused on video and has very little text. Either give me a transcript of what is in the video, or keep it to youtube.

Also, not directly a usability issue, but I think that the fast machines that most flash developers use leads them to not realize the impact that it carries on older machines and architecture. My laptop, for example, is a MacBook G4, and crals to a stop if there is more than one flash applet running in the page. I can kill it with myspace, for example.

I will say the most annoying one would be how Flash must be on top of everything, and a couple of pages i need to use have flash ads on the top header that something wont allow me to click on submenus(they appear with javascript but even with z-index:10000) its still under the flash ads

By far, sites that don't correctly deal with back/forward buttons. Some totally ignore them, others just freak out and put the session into a broken state.

Replacing the real life with the web.

Bear with me for a minute. When I wanted to travel to Mongolia, I needed to get a visa. I looked up the address of the Mongolian embassy on their website ^[1] (which only commits a few of the atrocities described here) and went there the next day. The building was somewhat hard to find and it was an extremely hot day, so I was already slightly annoyed by the time I got there. After waiting for a while, the clerk asked me if I had a certain printout with a barcode with me. I hadn't and told him I actually came to get all the paperwork from the embassy.

He informed me, that one can't apply for a visa at the embassy. The application has to be filled out online and printed on one's own printer (pray to god you have one), because some central server needs to spit out a barcode for you, something that apparently can't be done at the embassy.

But it gets worse: Trying to fill out the online form (which is on a completely different, even worse site ^[2] and wasn't linked to from the official embassy site at that time) you'll come across most of the other atrocities listed here. After filling out the 49 field form I noticed I couldn't submit it, apparently because some craptacular Javascript didn't work in anything but IE and wouldn't set the everything-a-okay flag.

If this would've been an online shop I'd've been long gone by then, but as it were I had to boot up Parallels and fill out the entire form a second time.

My worst online+offline experience ever. It seems they improved it slightly by now, but I think you still can't travel to Mongolia if you have no internet access and/or no printer.

Interstitial ads actually getting between me and the content I came there to see. Usability error, because I instantly stop using the site and go elsewhere.

www.lulu.com ^[1]

Buy a book, e.g. Delphi 2009 Handbook by Marco Cantu for $48.50 ^[2].

Add to cart. Price it says is $48.50.

Once you're at checkout and you see it adds $74.26 (!!!!????) for "Standard" shipping to Canada plus $6.14 tax totalling $128.90, are you going to continue your purchase or search around like mad to find out what the h-ll is going on. But finally, if you're persistent, you find the ground shipping at $16.43 which takes a whole 2 days longer than Standard.

I can't imagine the number of sales they must lose by not providing the cheapest shipping option in front of you right away, waiting until checkout to inform you of the shipping, and getting you mad before you find the cheaper (but still not cheap enough) shipping options. This is so horrible, I left their site with the view that I'll never publish anything myself with them.

So what can be a worse usability blunder than one that costs you customers?

Choose to eliminate: Abuse of Flash. Trying to read a page while in the periphery garish animations are competing for your attention ^[1]. Quickly drives me away from the page without reading what I came for, if I have that option, otherwise I'll waste some seconds trying to turn it off/zoom in so it's no longer visible.

Drop down lists/other controls that do auto post backs saving the page's form contents to the database without warning.

The worst of the worst

• very badly designed forms (e.g. credit card number without spaces or dashes, poor feedback on errors, etc.),
• "web pages" with flash animations instead of real content,
• still existing framesets and silly welcome pages,
• underlined text which is not link,
• enforced desktop metaphor,
• unreadable text (10px and co.),

and the list goes on. Maybe I should add missing functionality without JavaScript, but I don't want to start the flamewar again. These are just making webpages irritating to use.

edit: I forgot to mention the infinitely long dropdown lists (e.g. selecting your year and month of birth on some pages)

Non-sequential or non-logical tabindexes ticks me off.

Web forms with multiple fields that automatically set the focus to one of the fields.

Unless someone can give me a good reason why some sites do this ... I hate when I am not allowed to provide an email address with my username in it ... I am unable to use my email address with ebay because its nippysaurus@whatever

There's nothing I hate more than web forms that automatically tab based on the length of characters in the box. So if I'm typing in a phone number and I get a digit wrong, I click the box to fix the number. Except that the form forces my cursor to the next box.

And why ask for a phone number at all? This is the web. Don't call me, I'll call you.

Any upper limit on password complexity.

My bank disallows passwords with symbols in them.

Since they are (I hope) hashing the passwords, any such limit makes no sense.

Choose to eliminate: Wondering why a page is taking so long to load, only to find out it's to play some unwanted and irrelevant music. It's especially annoying if it's a page you'll have to come back to for a link to some other content, I'll just go elsewhere.

http://www.amazon.com/Prioritizing-Usability-VOICES-Jakob-Nielsen/dp/0321350316 ^[1]

Is the book that captures the trends and lists the top mistakes in recent web sites. It also studies the maturity in user behaviour through the past ten years or so.

Unfortunately, being a programmer at my firm, I have to create websites from already established PSD designs by the designer.

The other day, I had to turn a checkbox into a link, and on the same page, make a checkbox a submit button.

And my arguments fell on deaf ears, of course.

How about when governments make websites accessible only to users of a certain web browser?

Historic FAIL

From 1997.

I would say web pages that do not load ANYTHING unless you have JavaScript and cookies enabled for that site.

E-mailing you your actual password when you forget it instead of generating a random password and forcing you to change it the next time you log in.

Bad Time Warner Cable ^[1]! (It's really the PayXpress ^[2] bill pay system that is FUBAR)

When applying for some money to fund my education I had to answer an optional question given 2 possibilities. Both were made using radiobuttons (both unchecked) so I could only choose one of them. I misread the question and thought it was mandatory, so I clicked on of the buttons. After re-reading the question, it was obvious to me that I shouldn't have answered the question - so now what!? I couldn't uncheck my selection, had to reload the page, and fill in the entire (huge) form again.

Needless to say, the question was one of the last to be filled in :\

• Postbacks
• Crappy Javascript that shows error messages when doing anything
• Creating important popup windows when the page loads (= blocked by any popup blocker)
• Validating addresses in US format, making it impossible to enter perfectly valid addresses from other countries.

Usually it's within any website written by microsoft. They have a real knack for writing registration forms with infinite loops: fill them in, jump through all the hoops, and bingo, you are back to the beginning of the forms to start all over. A very close second are the codeplex or channel9 pages that make heavy use of ajax.

All time winner!!

Steps:

1. Google search on "sql express download".
2. You get the sql server express home page as the first hit. Go there and click the colored download box.
3. You get the register and download page. Skip the registration nonsense and click Download.
4. You get a highly confusing "fruit salad" download page with 6 different products. Search for and click the sql express 2008 box.
5. You get another similar register and download page. Click the more hidden "Download" link to skip the registration nonsense, again.
6. You get another download page. Click "Download now!". Sucker. http://www.microsoft.com/express/sql/download/
7. You get, wait for it...

Server Error in Application "DEFAULT WEB SITE" HTTP Error 404.0 - Not Found

All time winner in my opinion.

IE applications

Any app that assumes IE is not a "web application".

Not just on the web, but forms with mandatory fields that you cannot fill in either because you don't know and can't get the answer, or because the little list of options doesn't include the true answer, followed by a declaration that you're telling the truth.

(eg. I must fill in my drivers license or social security number - I don't have either)

Websites that won't run on Lynx ^[1].

The one that really makes my blood boil is when a webpage takes control of the back button so you can't leave the site. And its not only pr0n sites that do it!

Requiring a state to be entered for non-US postal addresses.

Solving navigation with JavaScript instead of hyperlinks, making the middle button on the mouse useless, because it won't open the target page in a new tab.

Sometimes links or buttons too close together, e.g. Submit and Reset on a form. Just a Submit button is good enough.

I encountered a form that has some pretty heavy calculations going on. In order to submit the form you have to get one of the hidden input fields to equal zero by entering 3 amounts that subtract from the hidden input field. The only way to tell if the required value is zero is by clicking a button which alerts the current value. Ultimately the flow looks something like this

1. enter all required fields
2. submit
3. receive error saying x has to be zero
4. enter an amount in field a to subtract from x
5. submit
6. receive an error that fields b and c are required
7. enter amounts in fields a, b, and c
8. click button to see if x is zero
9. repeat 7,8 until x is zero
10. submit

My two biggest usability beefs (very common in job application websites):

• You mess things up by opening new tabs when clicking on listed items (e.g., job postings), so that, for example, all opened tabs correspond to one of the selections rather than all of them.

• There is an in-page back and forward buttons and using the browser ones (or the mouse/keyboard buttons) messes things up.

Bouncing around with multiple domain names. If there's important processing on your page, don't delegate it to a script that's going to show up on NoScript with a dubious name.

Check out the HTML Hell Page ^[1], by Eric S. Raymond

The first time I used this internal website which also used some LDAP authentication/role-assignment; I was pretty pleased with everything.

Then I found there was no 'Log out/Sign out' button visible anywhere on the page; instead there was a hyperlink titled 'Log in as a different user'.

My banks web page which seems to have an onload event that clears the 12 character Internet Banking ID field when you are already half way through typing it in.

Flash based pages that hijack the function keys and other common keyboard short cuts.

Pages that disable the back button !!!!! (I really hate this one)

Pages that never seem to finish loading.

Pages that make you scroll for ages to get to important information or functions.

And last (and also least) pages that open links in the same window but when you hit the back button drop you in a different place on the page that you came from - forcing you to scroll back to your original departure point. Yes Stack Overflow, I'm talking about you!

An ecommerce site with a number of shortcomings ^[1] - the worst of which was the final payment page which has just two buttons:

Submit Payment and Payment

WTF?!

view fullsize ^[2]

As discussed in my article ^[1], the one that infuriates me most and forces the most loss of work is the asinine decision of browser vendors to make the backspace key to do a browser backwards navigation. Also complicit are the designers of software like Wordpress who will let an accidental backwards navigation erase all of your work in the text editor without so much as a confirmation.

Videos that start playing (or even buffering) when I open a page on a background tab.

Anything that doesn't actually work under either Firefox or Safari on the iPhone, for me. Second would be bad spacing, so images cover up text. (Presumably this would work on IE, but I'm not necessarily running Windows.)

Sony's PS3 operating system is a good example. Plug in a USB and discover that "X" does not show you it's contents, and pressing triangle actually also shows hidden files. Whoever thought of that is not a user interface guru.

An infinite redirect loop while trying to log into Microsoft's webmaster central.

I knew it could happen, but I'd never seen it happen before that.

Pages that contain both real content that I want to read, and an incidental search box in the top corner, that "helpfully" put focus in the search box, so I can't hit the Down arrow to scroll through the content.

Validating the phone number against a too strict format.

Not pre-populating a mailing address from zip ^[1] (or postal ^[2]) code, area code ^[3], and geo-ip ^[4].

The old Australian Westpac bank app was IE only. It made me upset.

www.myspace.com

A month or so ago, I was trying to renew my Flickr subscription and it failed for some unknown reason. Flickr did not give me any information as to why or who to contact. I tried a number of times that night and the next day with no success. Eventually I turned to Google to find a contact number for Flickr Billing. Turns out yahoo stored my old old address and assumed that this was still my billing address. The credit card company denied the initial transaction and my repeat attempts raised red flags. A week later I was finally able to renew...

I was AMAZED at how hard it was for me to give Flickr my money.

http://www.zonebbs.com is one big usability error. the creator of the site is blind and didn't bother asking anyone weather it looked decent. Although it's great if you use a screen reader I've been told it's painful on the eyes which helps explain why over 90% of it's members are legally blind.