I'm using ELK 6.5 currently vetting out the Platinum Trial (Xpack) and am attempting to send notifications using the Watcher service. When trying to send a 'test' email from Kibana, the following error message is generated:
"[cluster_block_exception] blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];"
Similar issues suggest this problem may be generated by low disk space, but the data nodes in our cluster have been cleaned to ensure we are far below the problematic threshold (currently only sitting around 12% memory usage). Our cluster is currently in a 'green' state with all shards having already been allocated. What else might cause this issue?