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Throw on Variable Not Found prevents a channel from sending when a variable in rendered content cannot be resolved. Enable it in the notification template’s Settings > Advanced section. For example, if your email template includes Hello {profile.first_name}, but first_name is missing from the user profile or the Send API profile object, Courier throws a render error for that channel. You can see the error in template preview and message logs: Preview
Screenshot of Variable Not Found on Preview
Logs
Screenshot of Variable Not Found on Logs

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Conditional Blocks

The check runs after all conditionals are evaluated and only inspects blocks that will actually be sent. If a block is hidden by a condition, its variables aren’t checked. For example:
  1. You add a conditional on profile.first_name to a text block.
  2. The block uses {profile.first_name}.
  3. The profile has no first_name, so the block is hidden by the condition.
  4. Throw on Variable Not Found does not trigger, and the message sends successfully.
Screenshot of a Conditional Block

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Multiple Channels

Each channel is checked independently. If {profile.first_name} appears in your email template but not in your Inbox template, only the email channel fails; Inbox still renders and sends.

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Observability

Render errors from this feature appear in Outbound Webhooks and Observability integrations under channel update events.

Variables

Insert dynamic values from data, profile, tenant, and brand objects.

Send Conditions

Control when notifications and channels send using conditional logic.