There is no procedure with the name `apoc.help` registered for this database instance. Please ensure you've spelled the procedure name correctly and that the procedure is properly deployed.
There is another answer for this error message, but the solution does not work in my case.
Here are details that I think may be relevant, on Ubuntu 20.04.
sfarnsworth@ubuntu:~$ neo4j --version
neo4j 4.1.12
sfarnsworth@ubuntu:~$ ls /var/lib/neo4j/plugins/
README.txt apoc-4.1.0.11-core.jar
sfarnsworth@ubuntu:~$ sudo neo4j restart
sfarnsworth@ubuntu:~$ cat /etc/neo4j/neo4j.conf | grep apoc
dbms.security.procedures.unrestricted=my.extensions.example,my.procedures.*,apoc.*
dbms.security.procedures.whitelist=apoc.coll.*,apoc.load.*
sfarnsworth@ubuntu:~$ cypher-shell
neo4j@neo4j> call apoc.help();
There is no procedure with the name `apoc.help` registered for this database instance. Please ensure you've spelled the procedure name correctly and that the procedure is properly deployed
This happens for any apoc call that I attempt.