Occasionally when adding nodes with OpsCenter, after the node list is populated and the installation process commences, the words "Error: Null" appear where the list of nodes and the corresponding progress bars should be displayed.
The initial symptom will be that the list of nodes to be installed and the progress bars vanish, replaced by the message "Error: Null" in the user interface. A confirming symptom will be the appearance of a stack trace ending in these lines in the ospcenterd.log:
File "build/lib/python2.7/site-packages/opscenterd/ClusterServices.py", line 333, in _makeAndStartServices
ERROR: Cluster provisioning failed: CancelledError:
ERROR: Failed to provision cluster: Cluster provisioning failed: CancelledError:
This is caused by the services OpsCenter uses to monitor the installation status taking longer to start than the default 30 seconds it is configured to time out at.
To resolve this, add the following to opscenterd.conf:
[clusters] add_cluster_timeout = <desired timeout interval in seconds>
and restart the opscenter process.