Thanks @twisted1919 , that will help me figure this out.@corey34 - most common reason is a timeout, when waiting too much for the data from the database server.
This is just a cleanup that mailwizz does.Oh it's also saying, "The export file has been deleted"
adjust not only php time settings, but also those in httpd/nginx), then restart webserverI think there's something else going on here. The first time I ran this, with a max_execution_time of 30 seconds, it went all the way to 100% before switching to a 400 error page. So I tripled the time to 90 seconds and tried again. Same results. If this was going to timeout it seems it would be doing it during the generation process, but I can see it adding emails. It's right at the very end that it looks like it fails. I can't find any corresponding error log entries for this though.