When your Business Rule isn't firing or is producing unexpected results, you need a systematic way to track down what's wrong. This guide walks you through the debugging tools and techniques that will isolate the problem.
Why Business Rules break silently
Business Rules fail in ways that aren't immediately obvious — they might not fire at all, fire at the wrong time, or execute but produce no visible effect. Unlike client scripts that can throw browser console errors, server-side Business Rules fail quietly. Platform admins and developers inherit these rules from previous teams, and without proper debugging techniques, you end up making changes blindly and hoping something sticks. The most common culprits are conditions that don't evaluate as expected, rules that are inactive or misconfigured for the wrong trigger, and logic errors that execute but don't produce the intended outcome.
How to systematically debug rules
Effective Business Rule debugging follows a specific sequence: first confirm the rule is configured to fire (active status, correct When settings, proper conditions), then verify it's actually executing (using logging and Script Debugger), and finally validate the logic inside produces the expected result. The Script Debugger lets you step through code line by line, but logging with unique prefixes is often faster for narrowing down where things go wrong. Most debugging sessions reveal that either the condition isn't being met when you think it should be, or the rule is firing but the logic has assumptions that don't match reality.
Building debuggable rules from the start
Once you've fixed the immediate problem, invest in making your Business Rules easier to debug next time. Add logging statements with unique prefixes that you can search for in System Logs. Structure your conditions to be testable — instead of complex multi-part expressions, break them into variables you can inspect. Use background scripts to test your rule logic against real records without triggering the actual rule. Well-debuggable rules have clear entry and exit logging, meaningful variable names, and conditions that can be easily validated in isolation.
Before you start
- •admin role or elevated_roles containing admin
- •Access to System Logs > All
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Step by step
Verify rule configuration basics
Navigate to System Definition > Business Rules and open your rule. Check that Active is true, then verify the When field matches your expectation — if you want the rule to fire on record updates, Update must be checked. For display business rules, remember they only fire when the form initially loads, not on field changes. Look at the Table field to confirm you're running against the right table.
Advanced conditions in the Advanced tab override the Filter Conditions tab entirely — check both locations.
Add logging to track execution
In your Business Rule script, add gs.log() statements with a unique prefix at the beginning and end. Use something like gs.log('INCIDENT_AUTO_ASSIGN: Rule started for ' + current.number, 'BusinessRule') at the top and gs.log('INCIDENT_AUTO_ASSIGN: Rule completed', 'BusinessRule') at the bottom. Add logging before and after any major logic branches or database queries.
Use a prefix that's easy to search for in System Logs — avoid generic terms like 'DEBUG' that will match too many entries.
Test the rule trigger
Make a change to a record that should trigger your Business Rule. For update rules, modify a field and save the record. For insert rules, create a new record. Navigate to System Logs > All and search for your unique prefix to see if the rule executed at all. If you see no log entries, the rule isn't firing.
Debug the condition logic
If the rule isn't firing, add temporary logging to your condition. For complex conditions, add gs.log('INCIDENT_AUTO_ASSIGN: Condition check - state=' + current.state + ', assignment_group=' + current.assignment_group, 'BusinessRule') before your main logic. Test again and check if the logged values match what you expect. Pay attention to empty values, which may be null, undefined, or empty strings.
Reference fields store sys_ids, not display values — log current.assignment_group.toString() to see the actual GUID being compared.
Enable Script Debugger for step-through
Navigate to System Diagnostics > Script Debugger and click Start Debugging Session. Set Transaction Filter to your table name and User Filter to your user name. In your Business Rule, add gs.log('Script debugger breakpoint', 'BusinessRule') where you want to pause execution. Trigger the rule again — when it hits that log statement, the debugger will activate and you can step through the code line by line.
Validate field values and timing
Use the debugger or logging to check that field values are what you expect when the rule runs. For before rules, remember that current contains the new values but previous contains the old values. For after rules, both current and previous are available but the database transaction is already committed. Log both current.field_name and previous.field_name for fields you're checking in your logic.
Test isolation and cleanup
Once you've identified and fixed the issue, remove debugging log statements that aren't needed long-term. Keep entry and exit logging if the rule is complex or business-critical. Run your test scenario again to confirm the rule works as expected, then stop the Script Debugger session from System Diagnostics > Script Debugger.
Best practices
Always use unique, searchable prefixes in gs.log() statements — 'INCIDENT_AUTO_ASSIGN' is better than 'DEBUG' or 'LOG'.
Remember that display Business Rules only fire on form load, not on field changes — use onChange client scripts for real-time field validation.
Check both Filter Conditions and Advanced tabs for condition logic — Advanced conditions completely override Filter Conditions when present.
Log the actual values being compared in conditions, not just true/false results — reference fields often contain unexpected sys_ids.
Don't leave Script Debugger sessions running in production — they impact performance for all users on that instance.
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