# Troubleshooting Omniscript validation and rendering errors

*Omnistudio Developer Study Guide · Troubleshooting and Debugging · Last updated October 27, 2026 · https://www.certifyforce.com/study-guide/omnistudio-developer/troubleshooting-and-debugging/troubleshooting-omniscript-validation-and-rendering-errors*

How to diagnose Omniscript validation that fires too late, custom error messages that never replace the original, conditional views that never match, repeat limits, toasts that vanish, and screens that behave differently in Preview than on the page.

- Certification: Salesforce Omnistudio Developer
- Exam section: Troubleshooting and Debugging
- Study guide: https://www.certifyforce.com/study-guide/omnistudio-developer

**Official exam objective:**

> Resolve Omniscripts errors or UI not rendering correctly.

## What the exam expects

- Make validation run while the user types instead of on blur.
- Write the Path and Value that let a Custom Error Message replace a Remote Action error.
- Fix a conditional view that never matches, including Date operands and hidden elements set to null.
- Set Limit Repeat for a maximum number of instances, and pick the Toast Mode that keeps a message visible.
- Separate documented Preview and element behaviour (mobile columns, Pattern, Mask) from real defects, and explain why a context ID that works in Preview fails on a page.

Key terms: **onBlur** (validation when the user leaves a field), **commitOnChange** (Setup JSON property that validates as the user types), **Custom Error Message** (Path, Value and Message that replace an error), **right operand** (the value a conditional view compares with), **Toast Mode** (how long a toast persists).

## Key facts

| Fact | Detail | Source |
|---|---|---|
| Default validation | Runs on blur (onBlur function) | [Display Messages](https://help.salesforce.com/s/articleView?id=xcloud.os_display_messages_in_omniscripts_19551.htm&language=en_US&type=5) |
| Validate while typing | Setup Edit as JSON: "commitOnChange": true; LWC delay half a second | [Display Messages](https://help.salesforce.com/s/articleView?id=xcloud.os_display_messages_in_omniscripts_19551.htm&language=en_US&type=5) |
| Custom Error Message Value | Must match the original error exactly, including spaces | [Error Messages](https://help.salesforce.com/s/articleView?id=xcloud.os_customize_omniscript_error_messages_10378.htm&language=en_US&type=5) |
| Nested error path | errors\|0:errorMessage | [Error Messages](https://help.salesforce.com/s/articleView?id=xcloud.os_customize_omniscript_error_messages_10378.htm&language=en_US&type=5) |
| Date right operand | ISO format, such as 2014-10-01T07:00:00.000Z | [Conditional View](https://help.salesforce.com/s/articleView?id=xcloud.os_conditionally_display_elements_using_the_conditional_view_property_19389.htm&language=en_US&type=5) |
| Hidden element | Its contents are set to null in the data JSON | [Conditional View](https://help.salesforce.com/s/articleView?id=xcloud.os_conditionally_display_elements_using_the_conditional_view_property_19389.htm&language=en_US&type=5) |
| Limit Repeat | 1 allows a maximum of two repetitions | [Element properties](https://help.salesforce.com/s/articleView?id=xcloud.os_common_omniscript_element_properties_definitions__10687.htm&language=en_US&type=5) |
| Toast Mode | Sticky until closed; Pester three seconds; Dismissable three seconds or until closed | [Element properties](https://help.salesforce.com/s/articleView?id=xcloud.os_common_omniscript_element_properties_definitions__10687.htm&language=en_US&type=5) |
| Context ID from Set Values | Works only in preview | [Preview](https://help.salesforce.com/s/articleView?id=sf.os_preview_an_omniscript_8849.htm&language=en_US&type=5) |
| "Inactive or not deployed" (Preview page) | Omniscript LWC can't exceed 4 MB | [Preview](https://help.salesforce.com/s/articleView?id=sf.os_preview_an_omniscript_8849.htm&language=en_US&type=5) |
| Similar error (Activation FAQ) | Insufficient object, field or record access, or missing Omnistudio object permissions | [Activation FAQ](https://help.salesforce.com/s/articleView?id=005232744&language=en_US&type=1) |

## Check yourself

- Why does an Omniscript show a validation message only after the user leaves the field?
- When does a Custom Error Message replace the original error?
- Why can a hidden Text element still trip a later validation check?
- Which Toast Mode keeps a toast visible until the user closes it?

## Sources

- [Common Omniscript Element Properties](https://help.salesforce.com/s/articleView?id=xcloud.os_common_omniscript_element_properties_definitions__10687.htm&language=en_US&type=5)
- [Conditionally Display Omniscript Elements](https://help.salesforce.com/s/articleView?id=xcloud.os_conditionally_display_elements_using_the_conditional_view_property_19389.htm&language=en_US&type=5)
- [Preview and Test an Omniscript](https://help.salesforce.com/s/articleView?id=sf.os_preview_an_omniscript_8849.htm&language=en_US&type=5)
- [Customize Omniscript Error Messages](https://help.salesforce.com/s/articleView?id=xcloud.os_customize_omniscript_error_messages_10378.htm&language=en_US&type=5)
- [Display Messages in Omniscripts](https://help.salesforce.com/s/articleView?id=xcloud.os_display_messages_in_omniscripts_19551.htm&language=en_US&type=5)
- [Common Action Element Properties](https://help.salesforce.com/s/articleView?id=xcloud.os_common_action_element_properties_11090.htm&language=en_US&type=5)
- [OmniScript Activation and Access Issues - FAQ](https://help.salesforce.com/s/articleView?id=005232744&language=en_US&type=1)

## About the full unit

The "Core concepts", "Exam traps" and "Worked scenario" sections of this unit, its 7 linked practice questions, and unlimited timed mock exams are included with the Omnistudio Developer pack (USD $19): https://www.certifyforce.com/practice-exams