Error with Transactional Emails

Question

The default english transactional email from Magento that is sent out to the customer has a CSS error in it and I am not sure what the solution is.
None of the styles load and at the top of the email I see:

{Error in template processing} {{inlinecss file="email-inline.css"}}

At the bottom of the email I see:

{Error in template processing}

Does this mean the email-inline.css file is missing?
My french transactional email display properly with no errors. Where would I find this file or how would I got about fixing this error?

Answer 1

That is actually related to code before the CSS directive. The code that processes the template is in Magento\Framework\Filter\Template::templateDirective():

public function templateDirective($construction)
{
    // Processing of {template config_path=... [...]} statement
    $templateParameters = $this->getParameters($construction[2]);
    if (!isset($templateParameters['config_path']) or !$this->getTemplateProcessor()) {
        // Not specified template or not set include processor
        $replacedValue = '{Error in template processing}';
    }
    ... //additional code omitted for brevity
}

As you can see, that error is used when the template config_path parameter is not set. I'd guess that that is most likely your issue: the template has likely been edited, and the parameter has been changed, malformed, etc.