All the FCB functions report an error by returning 0FFh in the AL register. Other functions report an error by setting the carry flag and placing an error code in the AX register. DOS 2.x functions return the error codes 0 - 12h. Under DOS 3.x, it is best to call function 59h to obtain more detailed error information.
Code MeaningCode Meaning 00h No error 22h Invalid disk change 01h Invalid function number 23h FCB unavailable 02h File not found 24h Sharing buffer overflow 03h Path not found 32h Network request not supported 04h No handle available 33h Remote computer not listening 05h Access denied 34h Duplicate name on network 06h Invalid handle 35h Network name not found 07h Memory control blocks destroyed 36h Network busy 08h Insufficient memory 37h Network device no longer exists 09h Invalid memory block address 38h Net BIOS command limit exceeded 0Ah Invalid environment 39h Network adapter hardware error 0Bh Invalid format 3Ah Incorrect response from network 0Ch Invalid access code 3Bh Unexpected network error 0Dh Invalid data 3Ch Incompatible remote adapter 0Eh Reserved 3Dh Print queue full 0Fh Invalid drive specification 3Eh Not enough space for print file 10h Attempt to remove the current 3Fh Print file was deleted directory 40h Network name was deleted 11h Not same device 41h Access denied 12h No more files 42h Network device type incorrect 13h Disk write-protected 43h Network name not found 14h Unknown unit 44h Network name limit exceeded 15h Drive not ready 45h Net BIOS session limit exceeded 16h Unknown command 46h Temporarily paused 17h Disk data error (CRC) 47h Network request not accepted 18h Bad request structure length 48h Print or disk redirection paused 19h Seek error 50h File exists 1Ah Unknown media type 51h Reserved 1Bh Sector not found 52h Cannot make directory entry 1Ch Printer out of paper 53h Critical-error interrupt failure 1Dh Write fault 54h Too many redirections 1Eh Read fault 55h Duplicate redirection 1Fh General failure 56h Invalid password 20h File sharing violation 57h Invalid parameter 21h File locking violation 58h Network device fault
The following information is returned by the DOS function 59h:
Error class:
Code Meaning 01h Out of resource 02h Temporary situation; try again later 03h Authorization 04h Internal error in system software 05h Hardware failure 06h System failure; serious failure of system software 07h Application software error 08h Item requested not found 09h Bad format (e.g., unrecognizable disk) 0Ah Item locked 0Bh Media error (e.g., CRC error) 0Ch Already exists 0Dh Unknown
Suggested action:
Code Meaning 01h Try again now. 02h Try again (a few times) after a pause, then prompt user to continue or abort. 03h Ask user to correct input, then retry. 04h Orderly abort; close files, then shut down the application. 05h Immediate abort; don't even try to close files. 06h Ignore. 07h Ask user to do something (like insert appropriate disk), then retry.
Locus of error:
Code Meaning 01h Unknown 02h Block device (e.g., disk drive) 03h Network 04h Serial device 05h Memory