You are replying to a thread which you did not start.
Are you certain that your problem is the same as the one discussed here in
all respects?
What version of Windows are you running, and what antivirus is installed?
We do try to give accurate advice, but it isn't always safe to generalize
from advice given to someone else whose details may differ in some way that
is significant.
It's generally better to start your own set of message by posting a new
message, describing what is happening on your system, and what you have
tried already to fix it.
I gather, from your response, that you are seeing this error message from
Windows Defender, perhaps on every startup of the computer? To help, we
need to know what version of Windows, and what antivirus is involved. There
are multiple causes of this particular error--the most frequent of which is
an antivirus product which attempts to disable Windows Defender, but doesn't
do this properly, hence the error message.