How to update Microsoft Defender Antivirus definitions on schedule

On Windows 10, the Microsoft Defender Antivirus updates automatically in the background, but if you disable automatic Windows Update, the option will also stop updates for the antivirus.

However, if you want to keep automatic updates disabled for Windows 10 while continue getting definition updates for Microsoft Defender Antivirus, you’ll need to create a schedule task to download updates automatically.

In this guide, you’ll learn the steps to download and update definitions manually for the Microsoft Defender Antivirus on Windows 10.

How to schedule task to definition update on Microsoft Defender
How to update definitions with Command Prompt on Microsoft Defender

How to schedule task to definition update on Microsoft Defender

To create a scheduled task to update Microsoft Defender Antivirus definitions, use these steps:

Open Start.
Search for Task Scheduler and click the top result to open the experience.
Right-click the Task Scheduler Library folder.
Click the New Folder option.
Type any name for the folder and click the OK button. (We’re creating a new folder to keep tasks organized and separated from the system tasks.)
Right-click the recently created folder, and select the Create Task option.

Task Scheduler create new task
In the “Name” box, enter a name for the task.
In the “General” tab, under the “Security options” section, select the Run whether user is logged on or not option. (This is the option that will make the command window not to appear when the task runs automatically.)

Task general settings
Clear the Do not store password option.
Click the “Triggers” tab, and click the New button.
Using the “Begin the task” drop-down menu, select the On a schedule option.

Task Scheduler trigger settings
Under the “Settings” section, select the Daily option.
Specify the Start settings on the right side.
Click the OK button.
Click the “Actions” tab.
Click the New Button.
Using the “Actions” drop-down menu, select the Start a program option.
In the “Program/script” box, type the following command:
```
"%ProgramFiles%\Windows Defender\MpCmdRun.exe"
```
In the “Add arguments” box, type the following command and click the OK button.
```
-removedefinitions -dynamicsignatures
```
Microsoft Defender clear definition cache
Click the OK button.
Click the New button again in the “Actions tab.
In the “Program/script” box, type the following command:
```
"%ProgramFiles%\Windows Defender\MpCmdRun.exe"
```
In the “Add arguments” box, type the following command and click the OK button:
```
-SignatureUpdate
```
Microsoft Defender update command
Click the “Settings” tab.
Check the following options:
- Allow task to be run on demand.
- Run task as soon as possible after a scheduled start missed.
- If the task fails, restart every. (Adjust as necessary.)
Click the OK button.

Task Scheduler additional settings
If prompted, enter your administrative username and password.
Click the OK button.

Once you complete the steps, the commands will run on the schedule you specified to update the Microsoft Defender Antivirus.

How to update definitions with Command Prompt on Microsoft Defender

If you want to update definitions without using Task Scheduler, the following instructions will help you to complete the task.

To update Microsoft Defender Antivirus definitions manually using Command Prompt, use these steps:

Open Start.
Search for Command Prompt and click the top result to open the experience.
Type the following command to clear the antivirus program cache and press Enter:
```
"%ProgramFiles%\Windows Defender\MpCmdRun.exe" -removedefinitions -dynamicsignatures
```
Microsoft Defender clean definition cache command
Type the following command to update Microsoft Defender Antivirus definition and press Enter:
```
"%ProgramFiles%\Windows Defender\MpCmdRun.exe" -SignatureUpdate
```
Microsoft Defender update definition with Command Prompt

After you complete the steps, Microsoft Defender Antivirus will contact the update servers to download and install the latest definition updates.