Virus definition file not updating
The definition files tell the scanner what to look for to spot viruses in infected files.
You can download virus definition file updates from the console, either immediately as a one-time task or as a regularly scheduled task.
Any time you change a global settings it is effective for all security content download tasks from that point on.
when i received a messgae that an issue was detected, so i open windows defender to resolve said issue and was successfully done.
However, if they need to be able to download the latest virus definition updates while they're not connected to the network (for example, while traveling or using a laptop), you can provide the option of letting users download files directly from the Whenever virus definition files are updated on managed devices, a mini-scan of memory processes runs on the device.
This scan is performed to ensure that the processes running in memory at the time of the update are still clean.