Zero bytes bases.cav file

Once again I have a bases.cav file of zero bytes.
This follows problems I had before with a similar problem.

I have completely uninstalled and installed again.

It’s almost as though the AV file update gets interrupted somehow. I don’t know how or why because everything else works OK and the connection to the Internet remains intact.

If I tell CIS to update the AV it starts the process then complains that the Internet connection has been interrupted. It hasn’t, I’m collecting mail and browsing at the time!

I then ask CIS to do a diagnostics and it complains that there is a problem (really?) and then crashes. I dutifully fill in the dialog about the crash and it brings up Thunderbird but a completely empty, uninitialised setup Thunderbird, no mail, no accounts, nothing. I’ve no idea how it does that. Again, no other program has a problem calling TB with a mailto: etc.

What amazes me id that CIS is quite happy to carry on without noticing this. If I didn’t now check several times every day I would continue to be unprotected.


Does it show version 0 or is the file size on disk 0 bytes?
That’s a bit strange because at boot-time CIS checks for corrupted bases.cav and should be able to detect this…

AV file has the proper version number in About…
The file size is zero bytes.

The file isn’t zero at boot up. It becomes so after the first update after turning on.

It’s just done it again as I write, this now seems to happen every day. The computer is busy doing other stuff, daily backups and CIS updates the AV and bases.cav is zero bytes long. I tell it to “Update Virus Database”, it fails with “Failed to update the virus signature database. Please check your Internet connection and try again later.”

There is nothing wrong with the connection. I did Diagnostics test, CIS said there is no problem! ???
At this point I normally copy over the bases.cav from the laptop and reboot. A right PITA.

I’ve watched the bases.cav file update and the file size as shown in Explorer is all over the place, it goes up and down every few seconds, 11MB, 70Mb, zero, 17Mb, 90Mb, zero. I don’t know how Comodo attach the incremental files to bases.cav, but it sure looks odd.
Somewhere, somehow, this is getting interrupted and the file left at zero bytes.

Remember, that I’m only sensitive to this problem and notice it because it has become a real issue and I check on it constantly. But as I sit here with a zero byte bases.cav file I’m unprotected. At some point CAV should need to use bases.cav to continue doing real-time scanning. Why doesn’t it notify me that the file is broken?

I do wonder how many other people go for days without a bases.cav file and not know it considering CIS only notices at boot up.


What version of CIS are you using? Notice that all versions starting with 3.12 and under do not get av updates anymore.

Always the latest version, currently

It’s not a case of not receiving updates any more, I do receive them and it makes a mess of the bases.cav file when it does.
On every occasion so far, when I’ve had to copy over another bases.cav file and reboot or reboot and let CIS get the new bases.cav, it has updated fine after that.
It seems to be the first update of the day shortly after switching on the computer, subsequent updates seem, so far, OK.


I think I’ve found the problem!

My daily backup software Second Copy happens to run and backup bases.cav just as it is being updated by CIS. Because of the strange way bases.cav is written to disk, not as a complete file but incremented with various file lengths, bits of it kkep being copied by Second Copy just as CIS is writing it to the disk and the resulting file gets broken.

This begs the question - why is bases.cav file written to the disk so unsafely?

Shouldn’t the incremental file be added to a copy of bases.cav and only when complete, does this replace the existing version?
As it stands, there are moments dependent on the amount of time it takes to update/Internet connection speed/how busy the server is etc when bases.cav is broken and incomplete.



In CIS v4 this mechanism has changed, I’m not sure if it will fix this problem but chances are it does…
Do you happen to have a test system or so you could try this CIS v4 beta and Second Copy on? to see if it’s fixed?

No Ronny I don’t, sorry.
I’m reluctant to try v4 at the moment on my computers.

Second Copy just copies the file onto another disk - nothing special. It would be trivial to set up a file copy on bases.cav whilst it is being updated to see what happens.

I hope v4 does save the bases.cav differently. To be honest I think it rather bizarre and against all the Comodo seems to stand for to update a live file in this way effectively taking it off-line whilst being updated and therefore vulnerable in this way.