Some customers may specify restrictive socketTimeout option, which would cause any long lasting DB statements to be interrupted with this timeout.

This may seem sensible during standard Web interactions where instance admins may want to interrupt long running queries. But at the same time it might be very harmful when applied during upgrade process, as it could easily leave database in the inconsistent state, being half upgraded from one version to another. In edge cases it may require manual intervention as db upgrade script may not allow to be rerun if partial changes were already applied.