This article is from a FAQ concerning SCO operating systems. While some of the information may be applicable to any OS, or any Unix or Linux OS, it may be specific to SCO Xenix, Open There is lots of Linux, Mac OS X and general Unix info elsewhere on this site: Search this site is the best way to find anything.
If that came from an application program, you might have to ask whoever wrote the program. However, if they are just showing you system error codes, or the error is coming from a system command, you can look in /usr/include/sys/errno.h to find an English translation. These errors are pretty standard across Unix/Linux systems, though where you'll find the list varies: on Linux, you can get it from "man errno".
See also https://aplawrence.com/Unixart/errors.html, where you would find this and more:
#define EIO 5 /* I/O error */ The catchall for all manner of unexpected hardware errors. It could be from a physical error, but additionally, an orphaned process (a process whose parent has died) that attempts to read from standard input will get this. BSD systems return this if you try to open a pty device that is already in use. An attempt to read from a stream that is closed will return EIO, as will a disk read or write that is outside of the physical bounds of the device. An open of /dev/tty when the process has no controlling tty will spit back EIO also.
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