There's no need for a config.sys file these days--if you are getting that
message, and have such a file, I'd recommend renaming it.
This message typically indicates either a firewall problem, or a machine on
a corporate or institutional network which doesn't allow direct access to
Windows Update. It can also indicate a machine which has been on such a
network in the past and hasn't been properly re-configured to access Windows
Update directly.
As an immediate work-around, please go to
www.microsoft.com/security/portal
Look in the right-hand column and download 32-bit Windows Defender
definitions. That will get you up to date for the time being.
To diagnose the rest of the issue, we need to know whether your machine fits
the description I gave above in any way--or whether you might have a
firewall installed which is preventing this access. Beyond that, we'd need
to see a portion of %windir%\windowsupdate.log.
To show us that log fragment, check the clock on your PC, then, in Windows
Defender, go to Help, Check for updates.
When the update attempt fails with this error, do:
start, run, and type the following line into the box:
notepad %windir%\windowsupdate.log
This may be a very large file. Scroll all the way to the end of the file,
then scroll back up to the time you noted before the check for updates.
Delete all the information BEFORE that check (don't worry--this is just
temporary.) Save the result to a new file with a .txt extension, or, simply
select/highlight it all and copy and paste it into a reply here.
The useful information will be near the beginning of the check for updates
where the names of the servers to be checked may be noted in the file.
