When connected to a metered connection, Windows 10 won’t download updates. This includes Windows Defender definitions.
Create a scheduled task to run the following command:
“c:\program files\windows defender\mpcmdrun.exe” –signatureupdate –mmpc
This is to run a signature update from the microsoft malware protection center (eg: Update from the internet).
The scheduled task can run as the user system, whether the user is logged in or not, and must be run with highest privileges.
If you want to test if your task is running correctly, you can run an elevated command prompt, issue the command mpcmdrun.exe -removedefinitions –all and then run the scheduled task. This initial download may take some time as it will do a full download, not just a dynamic update.
mpcmdrun.exe /? gives the following command line options:
Microsoft Antimalware Service Command Line Utility (c) 2006-2015 Microsoft Corp
Use this tool to automate and troubleshoot Microsoft Antimalware Service
MpCmdRun.exe [command] [-options]
-? / -h Displays all available options
for this tool
-Scan [-ScanType #] [-File <path> [-DisableRemediation] [-BootSectorScan]]
Scans for malicious software
-Trace [-Grouping #] [-Level #] Starts diagnostic tracing
-GetFiles Collects support information
-RemoveDefinitions [-All] Restores the installed
to a previous backup copy or to
the original default set of
[-DynamicSignatures] Removes only the dynamically
-SignatureUpdate [-UNC | -MMPC] Checks for new definition updates
-Restore [-ListAll | [-Name <name>] [-All] [-Path <path>]] Restore or list
-AddDynamicSignature [-Path] Loads a dynamic signature
-ListAllDynamicSignatures List the loaded dynamic signatures
-RemoveDynamicSignature [-SignatureSetID] Removes a dynamic signature
Support information will be in the following directory:
-Scan [-ScanType value]
0 Default, according to your configuration
1 Quick scan
2 Full system scan
3 File and directory custom scan
Indicates the file or directory to be scanned, only valid for custom scan.
This option is valid only for custom scan.
– File exclusions are ignored.
– Archive files are scanned.
– Actions are not applied after detection.
– Event log entries are not written after detection.
– Detections from the custom scan are not displayed in the user interface.
– The console output will show the list of detections from the custom scan.
Enables boot sector scanning; only valid for custom scan.
Timeout in days; maximum value is 30.
If this parameter is not specified, default value is 7 days for full scan and 1 day for all other scans.
Return code is
0 if no malware is found or malware is successfully remediated and no additional user action is required
2 if malware is found and not remediated or additional user action is required to complete remediation or there is error in scanning. Please check History for more information.
-Trace [-Grouping value] [-Level value]
Begins tracing Microsoft Antimalware Service’s actions.
You can specify the components for which tracing is enabled and
how much information is recorded.
If no component is specified, all the components will be logged.
If no level is specified, the Error, Warning and Informational levels
will be logged. The data will be stored in the support directory
as a file having the current timestamp in its name and bearing
the extension BIN.
0x2 Malware Protection Engine
0x4 User Interface
0x8 Real-Time Protection
0x10 Scheduled actions
0x4 Informational messages
0x8 Function calls
Gathers the following log files and packages them together in a
compressed file in the support directory
– Any trace files from Microsoft Antimalware Service
– The Windows Update history log
– All Microsoft Antimalware Service events from the System event log
– All relevant Microsoft Antimalware Service registry locations
– The log file of this tool
– The log file of the signature update helper tool
Scans for unusual files. The files and results of the scan
will be packaged in the compressed file.
Restores the last set of signature definitions
Removes any installed signature and engine files. Use this
option if you have difficulties trying to update signatures.
Removes all Dynamic Signatures.
Checks for new definition updates
[-UNC [-Path <path>]]
Performs update directly from UNC file share specified in <path>
If -Path is not specified, update will be performed directly from the
preconfigured UNC location
Performs update directly from Microsoft Malware Protection Center
List all items that were quarantined
Restores the most recently quarantined item based on threat name
One Threat can map to more than one file
Restores all the quarantined items based on name
Specify the path where the quarantined items will be restored.
If not specified, the item will be restored to the original path.
-AddDynamicSignature -Path <path>
Adds a Dynamic Signature specified by <path>
Lists SignatureSet ID’s of all Dynamic Signatures added to the client
via MAPS and MPCMDRUN -AddDynamicSignature
-RemoveDynamicSignature -SignatureSetID <SignatureSetID>
Removes a Dynamic Signature specified by <SignatureSetID>