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, software application, or computer hardware device. Proper design of error messages is an important topic in usability and other fields of human-computer interaction.

Here are some common computer-related error messages that occur in almost all programs and their causes:

• "Out of memory" - occurs when you have run out of memory or load too big of a file to store in RAM. The fix is to close some programs or get more memory.
• "You have run out of disk space" - occurs when the hard drive is full. When not enough memory is present, swap file is used and is stored on the hard drive. The fix is to close some programs (to free swap file usage) and delete some files, normally temporary files or get a bigger hard drive.
• Invalid page fault errors
• General protection fault errors
• The blue screen of death
• "File not found" - the file you were trying to open cannot be found. The file may have been damaged, moved, deleted, or a bug causes it
• "The device is not ready" - most often occurs when you have no floppy disk in the floppy disk drive and try to perform tasks involving the floppy disk or from a bad disk

Computer errors