Grover Throwing Javascript Timeout Error in Rails App

Question

I'm getting an error when rendering PDFs with Grover gem in a rails app:

Grover::JavaScript::TimeoutError: Timed out after waiting 30000ms

Couple key points:

Using Grover gem on rails 7 app
Fails in multiple areas grover is used, so points to grover issue or rails integration issue
When setting grover config to debug: true, the problem seems to go away
Issue on local development server and on Heroku production
The same exact code will execute properly, rendering the PDF on some requests within a second or two (seemingly pointing to random erroring, race condition, etc.)
When it hangs/times out, it does so indefinitely, increasing the timeout doesn't help

I've experimented with wait_until and other options on Grover, to no avail.

Mailer calling code...

  def send_invoice_to_email(emails, invoice_id)
    @invoice = Invoice.find(invoice_id)
    @company = @invoice.company

    html = ApplicationController.render(
      template: '/invoices/pdf',
      formats: :html,
      layout: 'pdf',
      assigns: {
        invoice: @invoice,
        company: @company
      }
    )
    pdf = Grover.new(
      html,
      format: 'A4',
      wait_until: 'domcontentloaded'
    )
    attachments[attachment_name(@invoice)] = pdf.to_pdf

    subject = "Invoice #%s" % [invoice_id]
    mail(to: emails, subject: subject, tag: 'INVOICE_SEND')
  end

Here is the failing test trace...

  2) InvoiceMailer Send invoice to email names attachment appropriately
 Failure/Error: attachments[attachment_name(@invoice)] = pdf.to_pdf

 Grover::JavaScript::TimeoutError:
   Timed out after waiting 30000ms
 # /usr/share/rvm/gems/ruby-3.3.6/gems/grover-1.2.1/lib/grover/processor.rb:93:in `call_js_method'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/grover-1.2.1/lib/grover/processor.rb:20:in `convert'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/grover-1.2.1/lib/grover.rb:51:in `to_pdf'
 # ./app/mailers/invoice_mailer.rb:24:in `send_invoice_to_email'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actionpack-7.2.2/lib/abstract_controller/base.rb:226:in `process_action'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actionpack-7.2.2/lib/abstract_controller/callbacks.rb:261:in `block in process_action'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/activesupport-7.2.2/lib/active_support/callbacks.rb:121:in `block in run_callbacks'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actiontext-7.2.2/lib/action_text/rendering.rb:25:in `with_renderer'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actiontext-7.2.2/lib/action_text/engine.rb:71:in `block (4 levels) in <class:Engine>'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/activesupport-7.2.2/lib/active_support/callbacks.rb:130:in `instance_exec'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/activesupport-7.2.2/lib/active_support/callbacks.rb:130:in `block in run_callbacks'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/activesupport-7.2.2/lib/active_support/callbacks.rb:141:in `run_callbacks'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actionpack-7.2.2/lib/abstract_controller/callbacks.rb:260:in `process_action'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actionpack-7.2.2/lib/abstract_controller/base.rb:163:in `process'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actionmailer-7.2.2/lib/action_mailer/rescuable.rb:29:in `block in process'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actionmailer-7.2.2/lib/action_mailer/rescuable.rb:21:in `handle_exceptions'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actionmailer-7.2.2/lib/action_mailer/rescuable.rb:28:in `process'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actionview-7.2.2/lib/action_view/rendering.rb:40:in `process'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actionmailer-7.2.2/lib/action_mailer/base.rb:657:in `block in process'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/activesupport-7.2.2/lib/active_support/notifications.rb:210:in `block in instrument'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/activesupport-7.2.2/lib/active_support/notifications/instrumenter.rb:58:in `instrument'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/activesupport-7.2.2/lib/active_support/notifications.rb:210:in `instrument'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actionmailer-7.2.2/lib/action_mailer/base.rb:656:in `process'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actionmailer-7.2.2/lib/action_mailer/message_delivery.rb:136:in `block in processed_mailer'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actionmailer-7.2.2/lib/action_mailer/message_delivery.rb:135:in `processed_mailer'
 # /usr/share/rvm/gems/ruby-3.3.6/gems/actionmailer-7.2.2/lib/action_mailer/message_delivery.rb:32:in `__getobj__'
 # ./spec/mailers/invoice_mailer_spec.rb:29:in `block (3 levels) in <top (required)>'

Templates...

PDF HTML Layout

<!doctype html>
<html>
  <head>
    <title>
      <%= content_for?(:title) ? yield(:title) : "PCI APP - PDF" %>
    </title>
    <meta charset='utf-8' />
    <%= stylesheet_link_tag "application_pdf" %>
  </head>
  <body style="background-color: #fff">
    <div id="content">
      <%= yield %>
    </div>
  </body>
</html>

Invoice PDF HTML template

<div id="invoice-pdf">

  <div style="padding: 20px; background-color: #fff">
    <%= image_tag 'logo_with_text_gray_inc.png', style: "margin-right: 10px; max-width: 300px;" %>
    <h1 class="text-muted float-end">Invoice</h1>
  </div>

  <hr>

  <div class="invoice p-3">
    <div class="invoice__header">

      <div class="invoice__meta-container">
        <div class="invoice__date float-end">
            <%= render partial: "invoices/invoice_meta", formats: :html %>
        </div>
        <div class="invoice__remit">
          <%= render partial: "invoices/remit_to", formats: :html %>
        </div>
        <%= render partial: "invoices/invoice_to", formats: :html, locals: {address: @billing_address} %>
      </div>
    </div>
    <div class="invoice__body">
      <hr>

      <div>
        <%= @invoice.notes&.html_safe %>
      </div>

        <%= render partial: "invoices/invoice_table", formats: :html %>
    </div>

    <p>
        Accepted payment methods: <b>Check, ACH, Wire Transfer, Bitcoin</b>.
    </p>
    <p>
      <b>We appreciate your business!</b>
    </p>
  </div> <!-- invoice -->

</div> <!-- #invoice-pdf -->

How can I fix the Javascript Timeout error?

Which line points to this ./app/mailers/invoice_mailer.rb:24:in `send_invoice_to_email' ? — Arup Rakshit
– Arup Rakshit, Commented Jul 23 at 20:10
It's the "to_pdf" call: attachments[attachment_name(@invoice)] = pdf.to_pdf — karns
– karns, Commented Jul 23 at 20:38
@engineersmnky I edited the question to show some templates. Pretty standard, I believe. — karns
– karns, Commented Jul 23 at 20:47

karns · Accepted Answer · 2025-08-14 20:43:16Z

0

A configuration mistake was leading to the error. The documentation points out that display_url is required, and mine was nil causing issues. My brain didn't connect this dot because of the random nature of the error.

Anyhow, adding display_url in the Grover configuration seems to have fixed the random timeout issues. I suppose the display_url being nil maybe triggered some sort of race condition.

Note that the full host name is important including http(s)://

/config/initializers/grover.rb

    display_url: Rails.configuration.x.grover.base_url,

/config/enviornments/[env].rb

  config.x.grover.base_url = "http://localhost:3000"

answered Aug 14 at 20:43

karns

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