Sierra 10.12.4 introduced undocumented changes in the log system which may break apps which write to the logs. Here is Blowhole fixed for that change.
bugs
Automated reporting of serious faults has helped Apple make macOS more reliable. But how do you report a bug which only the user can see?
Sierra 10.12.4 has had a lot of significant bugs fixed, at last. Here’s a list of those known to remain.
It worked for a little while, then stopped working again. Yes, it’s a bug.
In Sierra, does yours work properly, not work at all, or give you incorrect figures?
This command tool can now write just the integer passed to it as a log message. This is ideal for instrumenting scripts and apps for analysis.
This bug disrupts Time Machine backups and all the dozens of activities which macOS manages. It may make Sierra unsuitable for use in servers.
Here are two log excerpts which should be identical, but only one out of all the entries is actually the same. What is wrong?
Getting deeper into using Sierra’s new logs, and investigating why Time Machine backups become irregular.
Does macOS scheduling fail when it has been running for more than 10 days? Irregular backups suggest that it does.
The Eclectic Light Company 