Symptom:
Typing a letter into the Search Grid textbox in the upper right of the Virtual Resources pane causes "DSP operation failed." messages every refresh interval.

exception:java.lang.reflect.InvocationTargetException
reason:
description:
=> sun.reflect.GeneratedMethodAccessor6870.invoke [null -1]
=> sun.reflect.DelegatingMethodAccessorImpl.invoke [null -1]
=> java.lang.reflect.Method.invoke [null -1]
=> com.tidalsoft.framework.execute.CallMethod.execute [CallMethod.java 228]
=> com.tidalsoft.framework.execute.Batch$ExecuteInstance.execute [Batch.java 109]
=> com.tidalsoft.framework.execute.Batch.execute [Batch.java 58]
=> com.tidalsoft.framework.execute.Executor.execute [Executor.java 65]
=> com.tidalsoft.framework.execute.Executor.executeAsync [Executor.java 52]
=> com.tidalsoft.framework.execute.Execution.execute [Execution.java 24]
=> com.tidalsoft.webclient.tes.dsp.DataSourceProviderImpl.processRequest [DataSourceProviderImpl.java 739]
[...]

Conditions:
6.1.0.505m 506p
Recreate:
1.) Open the web client, click on virtual resources on the left
2.) Create a virtual resource if none exist
3.) Type the first letter of the newly created virtual resource into the search grid (or any letter)