JAVA_HOME not set; results may vary - no solution found

If you define JAVA_HOME in your environment, then you must use the command:
export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
And then the script will pick it up from your environment. Also please check if nifi bootstrap.conf file is configured properly. 

@Tokolosk JAVA_HOME is not required for nifi to operate.

[root@c7401 nifi-1.12.0]# ./bin/nifi.sh start
nifi.sh: JAVA_HOME not set; results may vary

Java home:
NiFi home: /root/nifi-1.12.0

Bootstrap Config File: /root/nifi-1.12.0/conf/bootstrap.conf

The only commands in my node are (not ubuntu but should be similar):

yum install java java-devel
wget http://apache.mirrors.hoobly.com/nifi/1.12.0/nifi-1.12.0-bin.zip
unzip nifi-1.12.0-bin.zip
cd nifi-1.12.0
./bin/nifi.sh start
tail -f logs/nifi-app.log
....

2020-09-25 12:15:14,828 INFO [main] org.apache.nifi.web.server.JettyServer NiFi has started. The UI is available at the following URLs:
2020-09-25 12:15:14,828 INFO [main] org.apache.nifi.web.server.JettyServer http://192.168.74.101:8080/nifi
2020-09-25 12:15:14,828 INFO [main] org.apache.nifi.web.server.JettyServer http://10.0.2.15:8080/nifi
2020-09-25 12:15:14,828 INFO [main] org.apache.nifi.web.server.JettyServer http://127.0.0.1:8080/nifi

If you are having problems, be sure to tail logs/nifi-app.log and look for errors.

If this answer resolves your issue or allows you to move forward, please choose to ACCEPT this solution and close this topic. If you have further dialogue on this topic please comment here or feel free to private message me. If you have new questions related to your Use Case please create separate topic and feel free to tag me in your post.

Thanks,

Steven