All the rules, except the SQL Functions, are executed through the AppBase Queue. The status of the execution can be monitored under Setup → Monitoring → Queue Monitor.

If custom rules have handling errors and don't have raise exceptions then AppBase executes through QUEUE as "No Error".

How to Catch Exceptions in NonSQL Rules.

BEGIN
  -- 
  -- SOME CUSTOM CODE
  --
   
EXCEPTION
  WHEN others THEN
    raise_application_error(-200001, 'Some exception error');
END;
SQL




How to Catch Exceptions in C# Rules

try
{
    //
    // SOME CUSTOM CODE
    //

}
catch (Exception e)
{
    throw new Exception (e.ToString());
}
C#