Error message

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An error message is a message displayed when an unexpected condition occurs, usually on a computer or other device. Error messages are often displayed using dialog boxes. Error messages are used when user intervention is required, indicate that a desired operation has failed, or give very important warnings such as being out of hard disk space. Error messages are pervasive throughout computing and are part of every operating system or computer hardware device. Proper design of error messages is an important topic in usability and other fields of human-computer interaction.

Common error messages

These computer-related error messages can occur in almost any program.

• File not found - The file concerned may have been damaged, moved, deleted, or a bug may have caused the error.
• The device is not ready - Most often occurs when there is no floppy disk (or a bad disk) in the disk drive and the system tries to perform tasks involving this disk.
• Access is denied - Occurs if the user has insufficient privileges to a file, or if it has been locked by some program or user.
• Out of memory - Occurs when the system has run out of memory or tries to load a file too large to store in RAM. The fix is to close some programs or get more memory.
• Low Disk Space - Occurs when the hard drive is full. To fix this, close some programs (to free swap file usage) and delete some files (normally temporary files, or other files after they have been backed up), or get a bigger hard drive.
• [program name] has encountered a problem and needs to close. We are sorry for the inconvenience. - Windows XP message displayed when a program causes a general protection fault or invalid page fault.
• The blue screen of death

Famous error messages

• Abort, Retry, Fail?
• Bad command or file name
• PC LOAD LETTER
• Lp0 on fire
• Not a typewriter
• Operation completed successfully
• Blue Screen of Death

Message format

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The format for error messages is not static and is dependent on many things. The three main factors^[1] that influence the format design are as follows:

Technical limitations

The strengths and restrictions of the technology one is working with should be among the first things taken into account when planning error messages. One must be careful to ensure that the medium he or she uses to communicate the error supports the size, shape, and style of his/her error message.

Amount of information presented

The nature of the error message will determine the amount of information required for the error message. If the error message is short –"Sorry, our Web site is currently undergoing maintenance, Please try again later." it may be more effective as a pop-up window than as a separately loaded page. This is because short messages can easily be drowned out if there is other content on the page. If there is no other content on the error message page, then the short error message will look out of place on a big empty page.

User input required

Finally, one should choose an error message format based on the type of input one requires from the user to correct a problem. Errors that simply inform the user of a problem that they can’t fix, such as a busy server on a website, are best suited to pop ups. In this situation, all one must do is inform the user of the problem, as no corrective action aside from trying again later. The only control available to the user should be the “OK” button. However, controls such as “Retry/OK” and “Cancel” should be used if the user is being prompted to corrective action. For example, “Windows encountered an error and needs to restart. Would you like to restart now?” should include an option to cancel and to restart. The buttons should correspond to the available options, i.e. “Restart now” button vs. “OK”, and “Later” vs. “Cancel”. This makes the options clearer to the user and thereby being conducive to correct decision making.

Presentation guidelines

The presentation and appearance of error messages are critical factors that influence heavily how well a user comprehends and responds to an error message. The following three principles^[2] should be adhered to when designing an error message:

Capture the user's attention

The visual attributes of an error message, including its color, size, and location can and should be used to grab the user’s attention and inform them that an error has occurred. Usually, the color red, a bold font, and the location at the top of the page and in front of any other window are good ways to allow the user to know that an error is present. In addition, an exclamation point is often used as an iconographic symbol to express importance.

Explain what went wrong

To effectively communicate with users, the application must speak their language. Messages must explain what the problem is using terminology that even a novice user can understand. The key idea here is to explain what went wrong, not just tell the user an error code. This is not to say to never include error codes in the error message. Instead, explain it in the proper context if it could prove useful. For example, an error message could reference error code 3555 and display the message “Please contact our help desk and reference error code 3555 for assistance”.

Show where error occurred and suggest possible solutions

Pointing users to solutions can be accomplished in many ways. The language used is an important factor in getting users to understand what went wrong and, consequently, how to fix it. For example, a poor error message might read, "You have entered an invalid string character in Field 123A". A better error message reads, "The zip code field contains an invalid character. Only numbers may be entered". Novice users won’t know what a 'string character' or 'field 123A' is, but they will recognize what the 'zip code field' and “numbers” are.

Additionally, the user can be shown exactly where the problem occurred by providing visual cues such as highlighting the field label with color, font treatment or iconographic images.

Once an error is located, instructions should be given to the user on corrective action, once again explained in the users’ language.

Providing examples of acceptable input is also a powerful technique for suggesting solutions for certain types of errors.

See also

• Human-computer interaction
• Interaction design
• Usability
• User interface design

References