Summary
A warning “schema version mismatch detected” occurs on restarting some DataStax Enterprise (DSE) nodes.
Applies to
- DSE 5.0
- DSE 6.0
- DSE 6.7
Symptoms
If some nodes are unavailable while restarting another node, the following warning occurs:
Warning: schema version mismatch detected; check the schema versions of your nodes in system.local and system.peers.
Cause
This error can be a false positive if some nodes are unavailable. This confusing error message when nodes are down is known behavior as tracked in CASSANDRA-11142.
Determine cause
Run the nodetool describecluster command:
nodetool describecluster
If the nodes are unreachable, the command output looks like this:
Cluster Information:
Name: Cluster12345abcde
Snitch: org.apache.cassandra.locator.DynamicEndpointSnitch
Partitioner: org.apache.cassandra.dht.Murmur3Partitioner
Schema versions:
UNREACHABLE: 1176b7ac-8993-395d-85fd-41b89ef49fbb: [10.202.205.203]
9b861925-1a19-057c-ff70-779273e95aa6: [10.80.207.102]
8613985e-c49e-b8f7-57ae-6439e879bb2a: [10.116.138.23]
Solution
- Restart unreachable nodes.
- Repeat step 1 until the output of the nodetool describecluster command shows that all nodes have the same schema version number and only one schema version appears in the output.