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An Attempt by process 'taskhostw.exe' to modify a backup file was blocked.

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This keeps popping up every once in a while. Not sure how to stop it or what it means with the options to "Ignore" or "Allow for One Hour". It is referring to the file that my full backup is in.

I would appreciate any explanations.


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Hello Gary,

Thank you for your posting! Most probably, some application is attempting to modify the backup archive. Are you using a third-party apps for synchronization that might try to access the backup location? An anti-virus software that performs a regular check? 

In reply to by Ekaterina

Posts: 3
Comments: 3


Hi Ekaterina,

I am only using Windows Defender and Virus that is a part of Windows 10.

Windows File History does write to a separate file folder on the same NAS that my Acronis Backup is written to, but they write to different files..

I have tried to make the C:\windows\system32\taskhostw.exe trusted on the Whitelist, however to do this you have to be in the Acronis Backup program and it claims the file cannot be found. However, when I search for it from Windows File Explorer I have no trouble finding the file.

It does not appear that if I click to "Ignore" or "Allow for one hour" that it affects anything. And in order to get rid of the warning screen, you have to select one of the two options.

It just seems to be more of a nuisance. 

Most appreciative for any suggestions.