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This page lists frequently asked questions and answers about ZooKeeper upgrading.

Upgrade to 3.5.5

Supported upgrade path: upgrading to 3.5.5 is only supported from a stable 3.4 version.

To get the best results it's strongly advised to upgrade to the latest stable 3.4 version before upgrading you ensemble to 3.5.5.

Error message: "java.io.IOException: No snapshot found, but there are log entries. Something is broken!"

This is a known issue in upgrading from 3.4 to 3.5. An extra startup check has been introduced in 3.5.5 (ZOOKEEPER-2325) to prevent a potential data inconsistency issue which makes ZooKeeper unable to start when no snapshot files present. It's a completely valid scenario in 3.4, so we have an open Jira to fix it: ZOOKEEPER-3056

The following workaround has been posted on the Jira and is known to be working:

To perform an upgrade (3.4 -> 3.5):

  • download the "snapshot.0" file attached (to the Jira)
  • copy it to the versioned directory (e.g. "version-2") within your data directory (parameter "dataDir" in your config - this is the directory containing the "myid" file for a peer)
  • restart the peer
  • upgrade the peer (this can be combined with the above step if you like)


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