PRB: Causes of DX1020 or R6915 Unhandled Exception Error

• Microsoft C for MS-DOS, versions 6.0a and 6.0ax
• Microsoft C/C++ for MS-DOS, version 7.0
• Microsoft Visual C++ for Windows, versions 1.0, 1.5, 1.51, and 1.52
• Microsoft Visual C++ 32-bit Edition, version 1.0
• Microsoft FORTRAN for MS-DOS, version 5.1
• Microsoft FORTRAN PowerStation for MS-DOS, version 1.0 and 1.0a
• Microsoft Macro Assembler for MS-DOS, versions 6.0, 6.0a, 6.0b, 6.1, 6.1a, and 6.11

SYMPTOMS

When you build an application in Microsoft C, Microsoft Visual C++, Microsoft FORTRAN, Microsoft FORTRAN PowerStation, or Microsoft Macro Assembler (MASM), one of the MS-DOS-extended development tools returns an unhandled exception error message such as:

   run-time error R6915 -
      DOSX16: unhandled exception

   DOSXNT : fatal error DX1020: unhandled exception:
      Stack fault;
   contact Microsoft Support Services

   DOSXNT : fatal error DX1020: unhandled exception:
      General protection fault;
   contact Microsoft Support Services

   DOSXNT : fatal error DX1020: unhandled exception:
      Page fault;
   contact Microsoft Support Services

CAUSE

Unhandled exception errors can be caused by a system configuration problem such as an ill-behaved device driver, a terminate-and-stay-resident (TSR) program, or a memory manager that is not configured correctly for the hardware in a particular machine.

RESOLUTION

Make backups of both the CONFIG.SYS and the AUTOEXEC.BAT files. Edit your CONFIG.SYS and AUTOEXEC.BAT files to remove all unnecessary device drivers and TSRs. You can typically get by with a CONFIG.SYS file that contains only a FILES= statement and a DEVICE=path\HIMEM.SYS. Depending on the hardware or configuration of a particular machine, other device drivers might be required. The AUTOEXEC.BAT file can contain a PATH statement and any required SET statements, but should not invoke any programs.

After creating clean CONFIG.SYS and AUTOEXEC.BAT files, shut down and restart your system. Try running the development tool that generated the unhandled exception error from the MS-DOS prompt, without starting Windows or any other programs. If at this point the problem goes away, substitute items back into your CONFIG.SYS and AUTOEXEC.BAT files until you can isolate which device driver or TSR caused the problem. If the problem occurs under Windows but not MS-DOS, try cleaning out your SYSTEM.INI file. If the problem does not go away, you will want to consult the Microsoft knowledge base for other causes of the error.