Seems a search turns up this post: Exception while running command(['/usr/bin/hostnamectl', '--static']): [Errno 24] Too many open files - #3 by tjr that says leaving the webui open for too long will cause this.
Seems a search turns up this post: Exception while running command(['/usr/bin/hostnamectl', '--static']): [Errno 24] Too many open files - #3 by tjr that says leaving the webui open for too long will cause this.