I recently updated Virtual Box from 5.2.24 to 6.0.4 and started to get these error.

I uninstalled Boinc and Virtual Box and reinstalled both but still got the errors.

The errors, so far, have disappeared when I changed from running 4 concurrent tasks with 2 cpus each to one task with 8 cpus.

I have SMT on but I limit the project to the number of 'real' cores.

I don't know if this will help any other users out and I also posted over on lhcathome.cern.ch since they have Virtual Box apps too.

Hi Jonathan,

I saw your post at LHC@home.
It seems VirtualBox 6.0.4 is more sensible for heartbeat issues with our vboxwrapper.
I downgraded my 6.0.4 version to v5.2.26 and restarted a postponed cosmology-task,
that already was postponed twice with version 6.0.4. The 3rd trial with v5.2.26 it succeeded.

http://www.cosmologyathome.org/result.php?resultid=5588234

Downgrading with Cosmo with suspended tasks works. LHC-tasks will error out, due to incompatibility 6.0.4 and 5.2.26 for the saved snapshots.

Thanks Crystal.