I've tried to start a single cluster 4 times on Databricks Community Edition today (13 March 2022). It's failed every time. Here's the first part of the output summary.
```
Time
2022-03-13 13:59:14 EDT
Message
Cluster terminated.Reason:Unexpected launch failure
An unexpected error was encountered while setting up the cluster. Please retry and contact Databricks if the problem persists.
Internal error message: com.databricks.backend.manager.instance.InstanceHolder$PlacementLockTimeout: Could not acquire placement lock context = requestResourcePlacement.
```