ID: Q167300
The information in this article applies to:
When you start a Win32-based application under Win32s, you encounter the following error:
DOS Error 21h
The purpose of this article is to provide you with a list of known reasons for this error under Win32s that have been reported to Microsoft and to suggest a workaround where applicable. Note that Microsoft is not suggesting or indicating that any of the reasons listed below are confirmed problems or bugs in the Win32s product, but we are only publishing customer reports on the DOS Error 21h.
If you are not running the latest Win32s version 1.30c (build 172), it is highly recommended that you upgrade to this build of Win32s. For further information on the Win32s upgrade, search for the PW1118 appnote in the Microsoft Knowledge Base.
Following are the possible reasons that have been reported to Microsoft for the DOS Error 21h under Win32s.
1. DOS Error 21h is a generic error produced by the Win32s loader when it
cannot find an associated DLL, EXE, or other file that the Win32-based
application needs while loading. For example, when you start a Win32-
based application, Win32s searches for the necessary Win32s files in the
Windows system and the Win32s directories, for any DLLs that the Win32-
based application is linking to, and any other files that the
application needs to load. If the Win32s loader does not find one of
these files, it displays the DOS error 21h message and terminates
loading the application. A commonly encountered problem is a missing or
an incorrect version of an ODBC DLL that a Win32-based application
requires to run. Ensuring that you have all the necessary files on your
Win32s machine is the first step in avoiding this error.
or earlier on a machine with greater than 32 Megabytes of physical
memory (RAM), then Win32s will generate the DOS error 21h. The error
occurs because Win32s version 1.30 and earlier do not support a physical
memory configuration of greater than or equal to 32 Megabytes. The
workaround for this scenario is to limit the size of virtual memory to
less than 256 MB. This can be done by reducing the PageOverCommit value
in the [386enh] section in the System.ini file. Note that valid settings
for this flag are between 1 and 20. Setting PageOverCommit to a value
larger than 4 results in less efficient usage of resources and slower
execution, but it allows you to run large applications that are
otherwise unable to run. Setting PageOverCommit to a value less than 4
does not allow some applications to run if their virtual memory
footprint is too high. The following expression should always be true
for 1.30 to work:
(PageOverCommit + 1) * RAM < 256M
NOTE: This problem was fixed in Win32s version 1.30a (build 166) and
does not occur in the latest Win32s version 1.30c (build 172).
your Windows computer has a UMC processor installed, the DOS Error 21h
occurs when you run a Win32-based application. Computers with UMC
processors are quite common in Canada.
NOTE: This problem was fixed in Win32s version 1.30a (build 166) and
does not occur in the latest Win32s version 1.30c (build 172).
Win32s and OLE files in your Windows 3.1 system directory as a result of
upgrading your previous installation of Win32s. Note that the Win32s
Setup.exe program is designed to run only under the retail version of
Win32s. If you have switched to the debug version of Win32s in the past
by using the Switch.bat file in the Win32s\Bin directory and then tried
to run the Setup program, Win32s will not be installed properly on your
computer (some of the Win32s and OLE files will not be replaced
correctly). In this case, the DOS Error 21h is followed by the message
"One of System Components is out of date".
NOTE: Do not use the Switch.bat program to upgrade a previous
installation of Win32s.
machine is an older version, not the one in Win32s version 1.30c. (Note
that the OLE version for Win32s 1.30c is 2.3.130.168.). In this case,
the error message appears and your application either starts and
continues to run, or the application does not start at all.
ARTICLE ID: Q159263
TITLE: PRB: "One of your System Components is out of date" Error
Novell networks. If you have a network installation of Windows on a
Novell network, and if the Windows system directory is mapped to the
root directory of any drive on the Novell network, the DOS error will
appear each time you start a Win32s application. However, the
application will start and continue to run. The solution is not to map
the Windows system directory to the root directory of any drive. Rather,
map it to a subdirectory on the drive. For example, if you mapped the
Windows system directory to W:\ drive, the workaround is to map the
Windows system directory to Z:\System directory on your Novell network.
filename (that is not in the 8.3 DOS file format), then Win32s would
display the DOS Error 21h message. This is because long filenames are
not supported under Windows 3.1.
3.1 machines, it has been reported that Win32s displays the DOS Error
21h message. Remove the offending software and see if the problem
goes away.
Windows 3.1 machines, it has been reported that Win32s displays the DOS
Error 21h message. The presence of F-PROT software is indicated by the
following line in the System.ini file:
device=C:\F-PROT\F-PROTW.386
To work around this, comment the above line in System.ini. Also, F-PROT
Professional version 2.19a is reported to be compatible with Win32s, so
upgrading to this version should resolve the DOS error 21h message.
Keywords : kberrmsg kbprg kbsetup kbtshoot kbWin32s kbfaq
Version : 1.3 1.3a 1.3c
Platform : WINDOWS
Issue type : kbinfoLast Reviewed: April 28, 1997