DOS Error Codes

 This topic lists error codes returned by DOS Functions (in AX when Carry
 Flag is set) as well as extended information returned by fn 59H.  Other
 error-code listings in TECH Help!:  APM API Error/Return Codes
                                     Device Driver Errors
                                     DoubleSpace API Error/Return Codes
                                     DPMI Error Codes
                                     EMM Error/Status Codes
                                     MRCI API Error/Return Codes
                                     POST Error Codes
                                     XMS Error Codes

 Error #                                Error #
 Hex Dec  Meaning                       Hex Dec  Meaning
 ▀▀▀ ▀▀▀  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀  ▀▀▀ ▀▀▀  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
 01H   1  Invalid function number       0aH  10  Invalid environment
 02H   2  File not found                0bH  11  Invalid format
 03H   3  Path not found                0cH  12  Invalid access code
 04H   4  Too many open files           0dH  13  Invalid data
 05H   5  Access denied                 0eH  14  (not used)
 06H   6  Invalid handle                0fH  15  Invalid drive specified
 07H   7  Memory ctrl blocks destroyed  10H  16  Can't remove current dir
 08H   8  Insufficient memory           11H  17  Not same device
 09H   9  Invalid memory block address  12H  18  No more matching files

█▌Extended Error Codes▐█
  These codes (and the class/location/action codes below) are returned by
  DOS fn 59H (DOS 3.0+).

 Error #
 Hex Dec  Meaning (returned in AX by Fn 59H)
 ▀▀▀ ▀▀▀  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
  0    0  No error (don't expect 0 unless no error has EVER occurred)

 13H  19  Write-protected disk ────────── 0 ┐
 14H  20  Unknown unit ID                 1 │
 15H  21  Disk drive not ready            2 │
 16H  22  Unknown command                 3 │
 17H  23  Disk data error (CRC error)     4 ╞═►These correspond to error
 18H  24  Bad request structure length    5 │  codes 0-0cH passed in DI to
 19H  25  Disk seek error                 6 │  an INT 24H critical error
 1aH  26  Unknown disk media type         7 │  handler and they match the
 1bH  27  Disk sector not found           8 │  values in AL after errors
 1cH  28  Printer out of paper            9 │  in INT 25H/26H.
 1dH  29  Write fault error             0aH │
 1eH  30  Read fault error              0bH │
 1fH  31  General failure  ──────────── 0cH ┘

 20H  32  File sharing violation
 21H  33  File locking violation
 22H  34  Invalid disk change
 23H  35  FCB unavailable (too many FCBs)
 24H  36  Sharing buffer overflow
 25H-31H  (reserved)
 32H  50  Network request not supported
 33H  51  Remote computer not listening
 34H  52  Duplicate name on network
 35H  53  Network name not found
 36H  54  Network busy
 37H  55  Network device no longer exists
 38H  56  Net BIOS command limit exceeded
 39H  57  Network adapter hardware error
 3aH  58  Incorrect response from network
 3bH  59  Unexpected network error
 3cH  60  Incompatible remote adapter
 3dH  61  Print queue full
 3eH  62  Not enough space for print file
 3fH  63  Print file was deleted
 40H  64  Network name was deleted
 41H  65  Access denied
 42H  66  Incorrect network device type
 43H  67  Network name not found
 44H  68  Network name limit exceeded
 45H  69  Net BIOS session limit exceeded
 46H  70  Temporarily paused
 47H  71  Network request not accepted
 48H  72  Print or disk redirection is paused
 49H-4fH  (reserved)
 50H  80  File already exists
 51H  81  (reserved)
 52H  82  Cannot make directory entry
 53H  83  "fail" error from INT 24H Critical Error handler
 54H  84  Too many redirections
 55H  85  Duplicate redirection
 56H  86  Invalid password
 57H  87  Invalid parameter
 58H  88  Network data fault

█▌Error Class▐█
  These codes provide additional information to help you determine how to
  handle the error.  Fn 59H returns these informational codes in BH.

 Class #
 Hex Dec  Meaning (returned in BH by Fn 59H)
 ▀▀▀ ▀▀▀  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
 01H   1  Out of resource: no more FCBs, memory, channels, handles, etc.
 02H   2  Temporary situation: will go away in a while (e.g., locked file)
 03H   3  Authorization problem:  You need higher permission to do this
 04H   4  Internal error: DOS is at fault
 05H   5  Hardware failure
 06H   6  System failure: DOS is at fault
 07H   7  App. error: passed bad info to DOS, inconsistent request,etc.
 08H   8  Not found: requested file/item can't be found
 09H   9  Bad format: file/item in invalid format (EXE file bad, etc.)
 0aH  10  Locked: file/item locked
 0bH  11  Media error: wrong disk, disk CRC error, etc.
 0cH  12  Already exists: collision with existing file/item
 0dH  13  Unknown error class: classification doesn't exist

█▌Suggested Action▐█
  These codes indicate appropriate action to take when an error occurs.  The
  idea is to limit your coding by NOT looking for specific error numbers in
  your application.  Instead, maintain upward compatibility by taking the
  suggested actions listed below.  Fn 59H returns these codes in BL.

 Hex Dec  Meaning (returned in BL by Fn 59H)
 ▀▀▀ ▀▀▀  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
 01H   1  Retry: Retry the operation a few times.  If the error continues
          to occur, ask the user if he wants to continue or quit.

 02H   2  Delay Retry: Delay a while and retry the operation a few times.
          If the error continues to occur, ask the user if she wants to
          continue or quit.

 03H   3  User Input: If data presented to DOS was entered by a user, ask
          the user to re-enter input (e.g., bad drive ID or pathname).

 04H   4  Abort: Abort the application, but it's OK to perform cleanup
          operations such as closing files, updating indexes, releasing
          memory blocks, etc.

 05H   5  Immediate Exit: Abort immediately without attempting cleanup.
          The system is in an unhealthy state and immediate exit is best.

 06H   6  Ignore: The error doesn't make any difference.

 07H   7  Retry after user action: the user needs to perform some action,
          such as inserting a diskette.  Prompt the user and then retry.

█▌Error Location▐█
  These codes are meant to help you figure out where the error occurred.
  Fn 59H returns these informational codes in CH.

 Locus #
 Hex Dec  Meaning (returned in CH by Fn 59H)
 ▀▀▀ ▀▀▀  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
 01H   1  Unknown: No specific area to pin-point error source
 02H   2  Block device: error occurred on disk or tape drive
 03H   3  (reserved)
 04H   4  Character device
 05H   5  Memory

█▌DOS Versions▐█
  Error handling is upwardly-compatible for all DOS versions.  These general
  rules apply:

    ■ DOS 1.x: indicates some errors by placing 0ffH in AL upon return.

    ■ DOS 2+:  New 2.0+ calls indicate errors by setting the Carry Flag
               (CF=CY=1) and putting an error code into AX.

    ■ DOS 3+:  2.0-6.0 calls still return error codes in AX when CF=CY.
               IBM advised us in 1985 to use DOS Fn 59H to obtain error
               information since this "AX return code" policy may change.
               But I don't see that happening.

See Also: DOS Fn 59H (get extended error info)
          INT 24H Critical Error Handling
          ErrorMode Flag
          APM API Error/Return Codes
          Device Driver Errors
          DoubleSpace API Error/Return Codes
          DPMI Error Codes
          EMM Error/Status Codes
          MRCI API Error/Return Codes
          XMS Error Codes