This form was missing from the server cache on Drupal 8

Question

On my site I do this:

I got a form with this field:

'myfile' => [
  '#title' => $this->t('MyTitle'),
  '#type' => 'managed_file',
  '#upload_location' => 'public://myfolder',
],

And MyController:

$myform = \Drupal::formBuilder()->getForm('Drupal\[mymodule]\Form\[myclassform]');

This variable I pass to Twig template.

On my template:

{{ myform }}

Every is ok.

But when the page is cached I got this error when i upload a file:

An unrecoverable error occurred. Use of this form has expired. Try reloading the page and submitting again.

I dont use memcache or CacheRoute, only drupal cache for anonymous user.

How I fix that? Is possible not cached the form?

Answer 1

I fixed that prevent that drupal cached the page, this way, because the forms can't be cached:

// Deny any page caching on the current request.    
\Drupal::service('page_cache_kill_switch')->trigger();

EDIT:

Recently was commited Add #cache[max-age] to disable caching and bubble the max-age

When $build['#cache']['max-age'] is not set, permanent cacheability (Cache::PERMANENT) is assumed.

To indicate that a render array is not cacheable at all, set $build['#cache']['max-age'] = 0 (i.e. zero seconds).

And to indicate that a render array is cacheable only for a limited amount of time, e.g. 5 minutes, set $build['#cache']['max-age'] = 300; // 5 * 60 = 300.