Validate that All Checklist Items are Complete
Company-managed Projects
This validator blocks a transition unless all items, including items on both local and Global Checklists are complete.
To set the workflow validator:
Navigate to Project Settings > Workflows
Click the pencil icon to edit the workflow.
Select Diagram mode and click on the transition where you want to add the validator.
Click on Validators.
Click Add validator.
Select the All checklist items are completed validator and click Add.
Click Add again to confirm creation of the validator.
Click Publish draft to save the changes.
Troubleshooting Validators
Checklists for Jira uses work item entity properties to provide the following features:
Therefore, the Checklist must be able to set work item entity properties. This is enabled by default. However, if a jira.permission.* workflow property has been set on a workflow step, Checklists may not be able to set issue entity property.
For example, the following property will prevent Checklists from setting work item properties, and features listed above won't work correctly:

Removing the jira.permission.* workflow property and using the standard Jira permissions to control who can edit the work item will allow the Checklist functions to work.
Team-managed Projects
You can create a rule in a Team-managed project that will block a transition unless all checklists on the work item (including items on both local and Global Checklists) are complete.
To create the rule:
Navigate to Project settings > Work types.
Select the appropriate work type. Use the Search all fields box to find the Checklist Completed custom field and drag it to the appropriate place on the layout. Click Save changes.
Click on the Edit workflow button.
Click Rule.
Select Restrict transition as the Rule type, and choose Restrict to when a field is a specific value. Click Select.
Select the appropriate transition.
Select:
Checklist Completed as the field
Text as the type
Equals as the condition
All Completed as the value
Click Add.
Click the Update workflow button to publish the rule.