The following applies only if you are upgrading from Logstash installations prior to 6.3.0 with the persistent queue enabled.
We regret to say that due to several serialization issues prior to Logstash 6.3.0, users will have to take some extra steps when upgrading Logstash instances with the persistent queue enabled. While we strive to maintain backward compatibility within a given major release, these bugs forced us to break that compatibility in version 6.3.0 to ensure correctness of operation. For more technical details on this issue, please check our tracking github issue for this matter, #9494.
If you are upgrading from Logstash 6.2.x or an earlier version and use the persistent queue, we strongly recommend that you drain or delete the persistent queue before you upgrade.
To drain the queue:
In the logstash.yml file, set
- Restart Logstash for this setting to take effect.
- Shutdown Logstash (using CTRL+C or SIGTERM), and wait for the queue to empty.
When the queue is empty:
- Complete the upgrade.
- Restart Logstash.
We are working to resolve issues with data incompatibilities so that these steps won’t be required for future upgrades.