Manually install the update definitions.
I would advise you to clear your cache, cookies, and history, as this will reduce scanning times by security software, press Ctrl-Shift-Delete – then shut down and restart your computer.
Go to-Get the latest definitions - Manually download the latest updates*<==***
<<https://support.microsoft.com/en-us/kb/923159>>
Switch back to Windows Defender and note the error code on the Home page. ***==>***If the error message that you received in Windows Defender contains code 0x80240016, restart your computer. ***<==***If the error message that you received in Windows Defender does not contain 0x80240016, go to Step 2.
Source:
<<https://support.microsoft.com/en-us/help/918355/>>
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Perhaps the following will help:
Problems starting Windows Defender in Windows 8/8.1/10 <<http://bit.ly/1SIMUSz>> crəated by PrashantKumar96.
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Pləase let us know what fixes the problem or if the pяoblem remains.
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