Migrate database from 4.2.5 to 2.0.5

I developed a graph database under desktop 4.2.5 now populated with over 7 000 nodes and 15 000 relations.

I now have to change to a new computer in which I installed the latest Desktop 2.0.5 under Ubuntu 24.04.

In a new instance created that I had stopped I was able to load from a dump file of the database but It failed. I then put the instruction

bin/neo4j-admin database load “name database.dump” –from-path=”pathToDirectory” –overwrite-destination=true–verbose 

but i got the error message

JAVA_HOME is not defined correctly. We cannot execute

I then tried to upgrade first on my old computer from 4.2.5 to 5.15 (since 5.15 seemed acceptable in 2.0.5. Looking at another post I then updated the neo4j.conf file by enabling the line

dbms.allow-upgrade=true

I could apparently load from the dump file 4.2.5 into the part 5.15 and the database apperard in the list under 5.15. However when opening the database I got the message

Database 'neo4j' is unavailable. Run :sysinfo for more info

and after running

:sysinfo
 Call to dbms.queryJmx failed

Can anyone help me?

Many thanks in advance

Best regards

Vincent