Can I check why a scan wasn't completed?

[MrSomeonesbody]

I made a full scan with Avast, but the next day, when I check scan History, it says the scan did not complete. This has happened thrice now and I can't figure out why.

Here is what I see: https://i.imgur.com/B2rqQEE.png

[Asyn]

Hi, Dave explained it here: https://forum.avast.com/index.php?topic=287085.msg1633224#msg1633224

[MrSomeonesbody]

 So is it nothing to worry about? Additionally, is there a way to check which files could not be checked scanned?

 Thank you for responding!

[DavidR]

I don't know if files that couldn't be scanned are reported by default (or just volume) in the scan report file.  However you would have to have enabled the Generate Scan Report. 

If so then the scan report file can be found here C:\ProgramData\AVAST Software\Avast\report the file name should match the name of the scan, see attached image.

[MrSomeonesbody]

 Thank you, turns out the problem was an error 0x0000A47E, which is a decompression bomb. Looking at the files that couldn't be read they mostly seem to be compressed files for modified videogame assets, so probably not a concern. Thank you for your help, I can finally sleep easy.

[DavidR]

You're welcome.

Decompression Bomb, a file that is highly compressed(as you found), which could be very large when decompressed. This used to be a tactic long ago to swamp the system. Now with modern computers this isn't so much of an issue

The name really is the most dangerous thing about this and I wish they would change it or simply not report it, a real PITA.

These highly compressed files are generally 'archive' files which are inert, don't present an immediate risk until they are unpacked. If you happen to select 'All packers' in your on-demand scans then you are more likely to come across this type of thing. Personally it is a waste of time scanning 'all packers' and that is why it isn't enabled by default.