No idea, sorry. That is a BitcoinZ node, not a Zcash node. I’ve never seen that error reported for Zcash nodes, and I have no insight into their codebase (including how far removed it is from Zcash now); you should ask on the BitcoinZ forums or issue tracker.
Problem was with entropy on the server. BitcoinZ is based on Zcash .
On my machine with Ubuntu entropy was around 150-300. BitcoinZ node need at least 1000 to correctly work.
The BitcoinZ devs have obviously replaced the RNG with one that can fail at the application level. We wouldn’t recommend that. It’s the operating system’s responsibility to provide a cryptographically secure source of randomness that can’t fail (short of the whole system being very broken). Zcash uses libsodium’s RNG API, which in the case of Linux is a wrapper around the getrandom syscall.