Error occurs every time I try to log in after updating I cloned a site locally, imported the database and run: "composer update --with-dependencies",

Got the following:


  [RuntimeException]
  Could not scan for classes inside
  "/home/www/sites/site/web/vendor/drexarj/disqus-php/disqusapi/" which
  does not appear to be      a file nor a folder


then I run "drush updb -y".

There were a couple warnings:


  The following module is missing from the file system: aspambot
  bootstrap.inc:268
  The following module is missing from the file system: phpmailer
  bootstrap.inc:268


Then I uninstalled recaptcha by typing:

"drush pm-uninstall recaptcha"

Tried to log in, but got the following unexpected error:


  The website encountered an unexpected error. Please try again later.
  Error: Call to undefined function Drupal\commerce_price\bcmul() in
  Drupal\commerce_price\Calculator::multiply() (line 75 of
  modules/contrib/commerce/modules/price/src/Calculator.php).
  Drupal\commerce_price\Calculator::multiply('107.000000', '1.00')
  (Line: 140) Drupal\commerce_price\Price->multiply('1.00') (Line: 259)
  Drupal\commerce_order\Entity\OrderItem->recalculateTotalPrice() (Line:
  133) Drupal\commerce_order\Entity\OrderItem->setUnitPrice(Object)
  (Line: 144) Drupal\commerce_order\OrderRefresh->refresh(Object) (Line:
  92) Drupal\commerce_order\OrderStorage->doPreSave(Object) (Line: 389)
  Drupal\Core\Entity\EntityStorageBase->save(Object) (Line: 820)
  Drupal\Core\Entity\Sql\SqlContentEntityStorage->save(Object) (Line:
  391) Drupal\Core\Entity\Entity->save() (Line: 114)
  Drupal\commerce_order\OrderStorage->postLoad(Array) (Line: 249)
  Drupal\Core\Entity\EntityStorageBase->loadMultiple(Array) (Line: 231)
  Drupal\commerce_cart\CartProvider->loadCartData(Object) (Line: 184)
  Drupal\commerce_cart\CartProvider->getCartIds(NULL) (Line: 172)
  Drupal\commerce_cart\CartProvider->getCarts() (Line: 221)
  Drupal\commerce_cart\Plugin\Block\CartBlock->getCacheTags() (Line: 86)
  Drupal\block\BlockViewBuilder->viewMultiple(Array, 'full', NULL)
  (Line: 71) Drupal\block\BlockViewBuilder->view(Object) (Line: 151)
  Drupal\block\Plugin\DisplayVariant\BlockPageVariant->build() (Line:
  259) Drupal\Core\Render\MainContent\HtmlRenderer->prepare(Array,
  Object, Object) (Line: 117)
  Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array,
  Object, Object) (Line: 90)
  Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object,
  'kernel.view', Object) call_user_func(Array, Object, 'kernel.view',
  Object) (Line: 111)
  Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch('kernel.view',
  Object) (Line: 156)
  Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line:
  68) Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1)
  (Line: 57) Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1)
  (Line: 47) Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object,
  1, 1) (Line: 99)
  Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line:
  78) Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1)
  (Line: 47)
  Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1,
  1) (Line: 52)
  Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1,
  1) (Line: 23) Stack\StackedHttpKernel->handle(Object, 1, 1) (Line:
  666) Drupal\Core\DrupalKernel->handle(Object) (Line: 19)


My question is: what can I do about this? I've repeated the process two times and got the same error.
Call to undefined function Drupal\commerce_price\bcmul() in Drupal\commerce_price\Calculator::multiply()


Drupal Commerce requires the BC Math PHP extension - you don't have it in your current environment.

To fix, rebuild PHP with support for the BC Math extension.