Windows Security failing to open is a deceptively common problem that can leave a PC exposed and users unnerved — yet in almost every case the root causes and remedies are resolvable without a full reinstall. Symptoms range from a completely unresponsive Windows Security app to a blank or...
app repair
appxpackage
defender
defender ui
dism
enterprise policy
event viewer
group policy
in-place repair
known issue rollback
powershell
reset windows security
securitycenter
sfc
system restore
third-party antivirus
windefend
windows defender
windows security
windows update