OpenNMS is not starting anymore.
Two scenarios are typical candidates that can cause OpenNMS is not starting.
Invalid configuration changes were made in
These files do not change by themselves.
An administrator must have changed files that causes now the starting issue.
Figure out what has changed and revert or correct it.
The upgrade process can also change configuration files. It’s always a good approach to check the Breaking Changes section in the release notes.
In case of upgrade configuration changes this article can help.
The install guides provides a versioned compatibility matrix you can use as reference.
Check the logs
output.log file should be investigated for problems.
To find issues in the log use:
grep -i 'error\|exception\|caused by' /var/log/opennms/output.log
In a Dockered OpenNMS the approach differs:
docker logs horizon 2>&1 | grep -i 'error\|exception\|caused by'
The configuration tester offers errors in the current configuration.
OpenNMS has to be able to resolve
localhost. The error that appears if it’s not possible looks like:
at org.opennms-netmgt.vmmgr.Manager.testGetLocalhost(Manager.java:248) ... Caused by: java.net.UnkownHostException: ...
Configuration Management Hint
To prevent configuration change issues in future it is a good approach to use Git to manage your configuration files to have a better overview about changes in configuration files.