I was trying to build a kraken database; however, I faced some challenges. I tried both the kraken standard database and custom database building procedures (according to the tutorial), but I receive a same error anyway in adding libraries phase:

rsync: change_dir "/refseq/bacteria" (in genomes) failed: No such file or directory (2)
rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1816) [Receiver=3.2.3]

For standard database I execute this command:

• kraken2-build --standard --db myDB ==> error

For custom database I execute these commands:

• kraken2-build --download-taxonomy --db myDB ==> run successfully
• kraken2-build --download-library bacteria --db myDB ==> error