Docs / Strand / advanced/error-handling

Error Handling

Learn how to handle errors in Strand workflows.

Overview

Errors can occur at various points in workflow execution. Strand provides several mechanisms for handling them gracefully.

Error Types

Node Execution Errors

When a node fails to execute:

• HTTP request fails
• Template rendering error
• Invalid configuration
• External service unavailable

Workflow Errors

• Infinite loop detection
• Invalid workflow structure
• Missing required fields

Error Handling Strategies

Default Values

Use the default filter to handle missing data:

{{ payload.email | default('[email protected]') }}

Conditional Checks

Check for data existence before using:

{% if steps.user_lookup.output_payload %}
  {{ steps.user_lookup.output_payload.email }}
{% else %}
  {{ 'No user found' }}
{% endif %}

Error Information

When a node fails, error information is available:

• Error message - Description of the error
• Error type - Category of error
• Node ID - Which node failed
• Timestamp - When the error occurred

Best Practices

Common Error Scenarios

Missing Data

Problem: Referencing data that doesn't exist

Templates render in strict mode: referencing a missing variable or key raises an error rather than producing an empty string. Depending on where the template runs, this can fail the step (If/Else conditions and sub-workflow inputs), set a field to null (Transform mappings), or pass the raw template text through (other node configs). Always guard optional fields.

Solution:

{{ payload.user.email | default('[email protected]') }}

See Jinja2 Error Handling for the full per-context behavior table.

Template Errors

Problem: Invalid Jinja2 syntax

Solution:

• Check syntax carefully
• Test templates incrementally
• Use execution logs to debug

Network Errors

Problem: External API unavailable

Solution:

• Use if/else branching to handle failure cases
• Configure retry logic on HTTP request nodes
• Provide fallback behavior

Related

• Conditional Logic - Using if/else branching
• Jinja2 Syntax - Safe data access

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