DatabaseBusyException: cannot create transaction

[dominikl]

Seen a few of these QAs recently. Might be just coincidence, but opened the issue to keep track of them.

QA 33016

java.lang.Exception: omero.gateway.exception.DSAccessException: Cannot access data. 
Cannot load hierarchy for class omero.gateway.model.DatasetData.
	at org.openmicroscopy.shoola.env.data.OMEROGateway.handleException(OMEROGateway.java:774)
	at org.openmicroscopy.shoola.env.data.OMEROGateway.loadContainerHierarchy(OMEROGateway.java:1649)
...
Caused by: Ice.UnknownException
    unknown = "ome.conditions.DatabaseBusyException: cannot create transaction
               	at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:289)
...

QA 32956