90020: One of 'TemplateArgs' dictionary key is blank

This error occurs when a template message request includes TemplateArgs and at least one dictionary key is blank. Use a non-empty key for every template argument so Twilio can match each substitution to the correct placeholder in the template.

• The TemplateArgs object includes an empty key.
• Your application builds TemplateArgs dynamically and one variable name resolves to a blank value before the request is sent.
• The request payload is serialized or transformed incorrectly, which leaves one of the TemplateArgs keys blank.
• A template tag is referenced in the template body, but the corresponding key in TemplateArgs is empty.

• Remove empty keys from TemplateArgs and resend the request.
• Make sure every TemplateArgs key is a non-empty string that matches the placeholder you want to populate.
• Validate and trim dynamically generated keys before you submit the message request.
• Review the final request payload your application sends and confirm TemplateArgs contains only valid key-value pairs.
• If you are building new template sends, use ContentSid with properly formatted ContentVariables in the Messages resource.

• Messages resource
• Using Variables with Content Templates
• Send WhatsApp notification messages with templates