Overview
The Block on Value option is a validation setting in the Form Template builder. It allows form administrators to configure a text or dropdown question so that when the question is submitted with a matching value from a previous form response, the user is blocked from submitting the form until the issue is resolved. This setting is configured on web in the form template and is enforced when users fill out the form on mobile.
Use Block on Value when a specific scanned or selected value indicates a problem — for example, if scanning a barcode that was already scanned on a prior form should trigger a warning and prevent further submission.
Accessing the Block on Value Setting
The Block on Value option is part of the Show Previous Response linking configuration in the Form Template builder.
From the navigation, click Forms, then click Form Templates.
Open or create the form template you want to configure.
In the form builder, locate the text (scan) or dropdown question you want to validate.
Click the link icon on that question to open the Show Previous Response modal.
Under Target Action, select Validate against linked value. The Block if value found and Block if no value found checkboxes appear.
How to Configure Block on Value
Before you begin:
Block on Value is only available on text questions (including continuous scan, tag scan, and VIN input types) and dropdown questions. It is not available on number, date, or other question types.
The question must be marked as required in the form template. If the question is optional, the blocking condition is never evaluated.
Steps:
In the Show Previous Response modal, configure the link settings:
Link to Form Template — select whether the previous response comes from the same form template or a different one.
Link From Question ID — select the question whose previous response will be used as the comparison value.
Link To Question ID — select the question whose answer will be validated.
Response From Question ID — select the question whose previous response is the value to compare against.
Lookback Hours — enter how many hours back to look for a previous response. Enter 0 for indefinite lookback.
Under Target Action, select Validate against linked value.
Select the blocking direction:
Check Block if value found to block submission when a matching previous response is found (e.g., preventing duplicate scans).
Check Block if no value found to block submission when no matching previous response exists (e.g., enforcing a prerequisite step).
NOTE: The two options are mutually exclusive — checking one automatically unchecks the other.
In the Validation message field, enter the message that will be shown to the user when they are blocked. This message is required and must be 512 characters or fewer.
Click Save.
NOTE: Block on Value is configured on web in the Form Template builder. The blocking enforcement happens on mobile — users filling out the form on mobile will see the validation message and be prevented from submitting when the condition is met.
Understanding Block if Value Found vs. Block if No Value Found
When "Validate against linked value" is selected, two blocking options are available:
Block if value found — Blocks form submission when the scanned or entered value matches a value found in a previous response within the lookback window. Use this when a match indicates a problem (e.g., duplicate scan, already-processed item).
Block if no value found — Blocks form submission when no matching previous response is found within the lookback window. Use this when a prior record is required before submission is allowed (e.g., a setup step must have been completed first).
Only one option can be active at a time. Both options require a Validation message — this is the text shown to the mobile user when they are blocked.
Use Cases
Quality control scanning — A technician scans a component barcode during a maintenance form. If that barcode was already scanned on a previous form within the last 24 hours, "Block if value found" prevents the form from being submitted again — helping catch duplicate work orders or accidental rescans.
Sequential process enforcement — A form requires that a specific serial number was recorded in a prior intake form. "Block if no value found" prevents submission until a prior response with that serial number is found, ensuring steps are completed in order.
Asset tracking with a lookback window — By setting Lookback Hours to 8 (one shift), a team can configure validation that only checks within the current shift window — so prior-shift data does not trigger false positives.
Best Practices
Write clear validation messages: The message you enter is shown to the mobile user when they are blocked. Write it in plain language that tells them exactly what to do — for example, "This barcode has already been scanned today. Check with your supervisor before proceeding."
Use Lookback Hours to scope the check: A lookback of 0 checks all history, which may cause unexpected blocks for legitimate reuse of values over time. Set a specific lookback window that matches your workflow (e.g., 8 hours for a single shift, 24 hours for a daily check).
Confirm the question is required: Block on Value only enforces on mobile when the question is required. If the question is optional, users can skip it entirely and the blocking condition is never evaluated.
Troubleshooting
Issue: The "Validate against linked value" option is not visible in the form link modal.
Solution:
Confirm the question type is text (including scan, tag scan, and VIN input types) or dropdown.
If the question is a number, date, or other type, the validate option is not available for that question type.
Change the question type in the form template if the validate option is needed.
Issue: The "Block if value found" and "Block if no value found" checkboxes appear but I cannot check both at the same time.
Solution:
This is expected behavior — the two options are mutually exclusive.
Checking one automatically unchecks the other.
Decide which direction of blocking your workflow requires and select only that one.
Issue: The validation message field is required but I do not see it.
Solution:
The validation message field only becomes required (and editable) after you check either "Block if value found" or "Block if no value found."
Check one of the blocking options first, then enter your validation message before saving.
Issue: The block is not triggering on mobile even though it is configured.
Solution:
Confirm the question is marked as required in the form template. Blocking only enforces when the question is required.
Check the Lookback Hours setting. If the lookback window is too short, a prior response may be outside the window.
Verify the Link From Question ID and Link To Question ID are correctly configured to point to the right questions.
Re-save the form template and ask the mobile user to sync before retesting.
Summary
Block on Value is a form validation option that lets administrators configure a text or dropdown question to block mobile form submission when a matching — or missing — previous response is detected within a defined lookback window. It is configured in the Form Template builder on web under Show Previous Response > Validate against linked value, and it enforces on mobile. Always write a clear validation message, confirm the question is required, and test on mobile before publishing the form template.