Exception Handling
The exception model
Blue Prism distinguishes System Exceptions (raised by the platform, for example when a stage fails or an element is not found) from Business Exceptions (raised deliberately when a business rule is violated, such as an invalid account number). Candidates must know how to raise each, and why the distinction matters for reporting and retry behaviour.
Recovery and resume
Understand the Recover stage, which is placed on a page to catch exceptions, and the Resume stage, which returns control to the calling page. Know that a Recover stage must be paired with a Resume stage, and that the Block containing the recoverable logic determines the scope. Understand the Exception stage's ability to raise a business exception with a custom message, and the Preserve option on blocks that keeps exception detail.
Retry patterns
Know the standard retry pattern: a loop with a counter, a Recover block around the risky action, and a decision to retry up to a limit before escalating. Understand that retries should be bounded and that exhausted retries should raise a business exception or route to a work queue exception item.
Traps to watch for
Frequent traps include: assuming a Recover stage catches exceptions from pages it calls (scope matters), forgetting that Resume is required, confusing system and business exceptions in reporting, and swallowing exceptions silently. Another trap: placing recovery logic inside the object rather than around the object call in the process.
Rule of thumb
Recover should wrap the smallest unit of work you are willing to redo. If redoing it would cause duplicate side effects, make the action idempotent first.
Control Room Operations and Governance
What Control Room governs
Control Room is the operational surface for running and governing automation. Candidates must understand Processes, Business Objects, Work Queues, Schedules, Sessions, Resources, Environment Variables, Credentials, Roles, and Audit Logs.
Work queues
Know the queue item lifecycle: New, In Progress, Exceptioned, Completed, and Deferred. Understand how a process gets the next item, how items are locked to a session, how deferral works with a retry date, and how exception items are inspected and retried. Understand queue priorities and how they affect item selection.
Scheduling and resources
Understand schedules: frequency, start and end times, and which resource runs them. Know that a resource is a runtime machine with a licence, and that sessions are the execution instances. Understand how to pause, stop, and terminate a session, and what state each leaves the process in.
Security and governance
Understand roles and permissions, credential management (credentials are stored encrypted and referenced, not exposed), environment variables for configuration, and the audit trail. Know that changes to processes should follow release and versioning discipline.
Traps to watch for
Questions often test the difference between stopping and terminating a session, whether a deferred item becomes available immediately, and whether credentials can be read as plain text. Another trap: assuming a schedule can run without an available resource.
Rule of thumb
Anything that differs between environments belongs in an Environment Variable; anything secret belongs in a Credential. Never hard-code either.