I was encountering this error in a FIM Workflow with an If-Else statement that was using a Declarative Rule Condition where the declarative rule condition name was the “condition name”.
The fix was to add something like the following in the code behind:
private void ccManagerEmailFound(object sender, ConditionalEventArgs e)
{
e.Result = bManagerEmailFound;
}
Then, change the If-Else to a Code Condition and select the new code condition just added.
This could be the problem. Ran into it myself
https://idmgnt.wordpress.com/2013/12/03/custom-workflow-condition-unable-to-evalute/