simple.slim

initialize() {
  initializeMutationRate(1e-8);
  initializeMutationType("m1", 0.5, "f", 0.0);
  initializeGenomicElementType("g1", m1, 1);
  initializeGenomicElement(g1, 0, 99999);
  initializeRecombinationRate(1e-8);
}


1 early() {
  sim.addSubpop("p1", 100);
  log = sim.createLogFile("log.tsv.gz", compress=T, sep="\t", logInterval=10);
  log.addGeneration();
}

2000 late() {
  sim.simulationFinished();
}

I get

#ERROR (Eidos_WriteToFile): encountered zlib errors while writing to file at path log.tsv.gz.

Is this what happens to you?

Yup, exactly. Thanks! I can submit an issue.