Had an update to Avast Pro today, restarted the pc and now everytime I try a Smart scan or a Network scan Avast disappears and no scan is performed.
A full virus scan works but for some reason the other two don’t and are bugged. I’ve since uninstalled Avast and reinstalled it which didn’t help and tried updating the Pro Antivirus to the new Premium Security version. Again same problem. I’ve restarted my pc several times and can’t find a fix. For some reason it just stops working.
Sounds the same as my issue. Looks like it may be a bug in the update. I didn’t try a full scan but will now.
I have the same problem with my Avast Premier ! :-[
Please Avast, send corrections urgently !
Seems to be the main application that crashes every time. Even after restoring the default settings and using avastclear.exe to perform a clean installation I’m still getting the same problem.
Not sure why it’s started, but it was telling me to restart my pc after an automatic update and it started after that so I hope a fix comes out soon.
For now I’m just letting the program run in the background and staying away from the Smart Scan with Windows Defender turned on.
Avast has acknowledged the problem and is working on a fix.
Exactly the same problem here.
I am having the exact same problem with my new Premium. the complete scan still works, but the program always crashes, when I try to start a network- or smart-scan. Repairing and reinstalling didn’t help one bit. I hope this is fixed quickly.
If you read the reply, you would already have known that Avast is aware of the problem and is working on a fix.
Posting me too doesn’t doesn’t really do anything. Have a little patience. 
FYI. See Avast acknowledgement of the problem and expectation of a fix here:
https://forum.avast.com/index.php?topic=231475.msg1531638#msg1531638
It’s fixed. (Restart your computer)
https://screencast-o-matic.com/screenshots/u/Lh/1578655279911-52226.png