Full ERROR Message Example
ERROR [main] 2020-09-04 13:20:56,040 Directories.java:116 - Not a directory /var/lib/cassandra/saved_caches_test
Note: For the purposes of this test, I created a text file called saved_caches_test and replaced the saved_caches_directory in the cassandra.yaml to point to this file instead of the saved_caches directory.
What does this ERROR message mean
It means the directory name you provided in the directory path, whichever path this may be, is not in fact a directory.
Why does this ERROR occur
This error occurs because you are trying to configure certain parameters in configuration files to point at a directory that isn't in fact a directory, but most likely a file.
How do you fix this ERROR
Check the directory name mentioned in the error message across all nodes in the cluster, and confirm if the intended directory you planned to use exists as a file.
If you do not see any problems, consider creating (if this is a tarball installation) and then navigating to that directory.
If you receive a command line error similar to the below, it means the directory does not exist as a directory.
$ cd /var/lib/cassandra/saved_caches_test bash: cd: filename: Not a directory
If you are unable to create this directory for a known reason, consider altering cassandra.yaml to use an alternate directory.
NOTE: Any changes in the cassandra.yaml file will require a restart of the C*/DSE service for them to take affect.