Tar pipe to xz results in broken pipe

I have a backup script that runs the following commands: tar -c dir1 dir2 | xz -9 -T0 | gpg -c --batch --passphrase xxx | aws s3 ... The return values are always the same: tar fails with 141 (broken pipe error) and xz returns 137 (no other error messages, even in verbose mode). The script is tested, runs as root and works well on other servers. Initially I thought that the data I'm backing up could be corrupt and deleted some socket files within the backup directory (which is a rsnapshot folder), but that hasn't helped as well. Does anyone have an idea what the problem could be? EDIT: If I remove xz from the pipe it works.