Body: <p>I migrated to craft 4 according to the migration guide and everything went well.
  Steps to reproduce</p>
  <ol>
  <li>Migrate to craft</li>
  <li>Add something into the cart</li>
  <li>On the Cart template there is the following error on the cart page:</li>
  </ol>
  <blockquote>
  <p>craft\commerce\services\Discounts::getDiscountByCode(): Argument #1
  ($code) must be of type string, null given, called in
  /Users/atelierworkstation/Documents/git-local/atelier-shop/vendor/twig/twig/src/Extension/CoreExtension.php
  on line 1607</p>
  </blockquote>
  <pre><code>TypeError: craft\commerce\services\Discounts::getDiscountByCode(): Argument #1 ($code) must be of type string, null given, called in /vendor/twig/twig/src/Extension/CoreExtension.php on line 1607 and defined in /vendor/craftcms/commerce/src/services/Discounts.php:382
  Stack trace:
  #0 /vendor/twig/twig/src/Extension/CoreExtension.php(1607): craft\commerce\services\Discounts-&gt;getDiscountByCode(NULL)
  #1 /vendor/craftcms/cms/src/helpers/Template.php(110): twig_get_attribute(Object(craft\web\twig\Environment), Object(Twig\Source), Object(craft\commerce\services\Discounts), 'getDiscountByCo...', Array, 'method', false, false)
  #2 /storage/runtime/compiled_templates/48/4814239c41dedafc8391a1b70140a2d5.php(59): craft\helpers\Template::attribute(Object(craft\web\twig\Environment), Object(Twig\Source), Object(craft\commerce\services\Discounts), 'getDiscountByCo...', Array, 'method')
  #3 /vendor/twig/twig/src/Template.php(171): __TwigTemplate_fc9f511b5bd2fbee71b2e2d81933d7e6-&gt;block_main(Array, Array)
  #4 /storage/runtime/compiled_templates/1c/1c64b2042fe0dfe96716d9e6f05f4b31.php(332): Twig\Template-&gt;displayBlock('main', Array, Array)
  #5 /vendor/twig/twig/src/Template.php(171): __TwigTemplate_f939a9e67f563b6befd17836bf1b98ec-&gt;block_body(Array, Array)
  #6 /storage/runtime/compiled_templates/1c/1c64b2042fe0dfe96716d9e6f05f4b31.php(304): Twig\Template-&gt;displayBlock('body', Array, Array)
  #7 /vendor/twig/twig/src/Template.php(394): __TwigTemplate_f939a9e67f563b6befd17836bf1b98ec-&gt;doDisplay(Array, Array)
  #8 /vendor/twig/twig/src/Template.php(367): Twig\Template-&gt;displayWithErrorHandling(Array, Array)
  #9 /storage/runtime/compiled_templates/06/06430c5474c19a0e396cb203c104bc63.php(53): Twig\Template-&gt;display(Array, Array)
  #10 /vendor/twig/twig/src/Template.php(394): __TwigTemplate_f1d0c467d20bbb79bcf56d6786094c73-&gt;doDisplay(Array, Array)
  #11 /vendor/twig/twig/src/Template.php(367): Twig\Template-&gt;displayWithErrorHandling(Array, Array)
  #12 /storage/runtime/compiled_templates/48/4814239c41dedafc8391a1b70140a2d5.php(46): Twig\Template-&gt;display(Array, Array)
  #13 /vendor/twig/twig/src/Template.php(394): __TwigTemplate_fc9f511b5bd2fbee71b2e2d81933d7e6-&gt;doDisplay(Array, Array)
  #14 /vendor/twig/twig/src/Template.php(367): Twig\Template-&gt;displayWithErrorHandling(Array, Array)
  #15 /vendor/twig/twig/src/Template.php(379): Twig\Template-&gt;display(Array)
  #16 /vendor/twig/twig/src/TemplateWrapper.php(40): Twig\Template-&gt;render(Array, Array)
  #17 /vendor/twig/twig/src/Environment.php(277): Twig\TemplateWrapper-&gt;render(Array)
  #18 /vendor/craftcms/cms/src/web/View.php(451): Twig\Environment-&gt;render('purchase/cart', Array)
  #19 /vendor/craftcms/cms/src/web/View.php(504): craft\web\View-&gt;renderTemplate('purchase/cart', Array)
  #20 /vendor/craftcms/cms/src/web/TemplateResponseFormatter.php(56): craft\web\View-&gt;renderPageTemplate('purchase/cart', Array, 'site')
  #21 /vendor/yiisoft/yii2/web/Response.php(1098): craft\web\TemplateResponseFormatter-&gt;format(Object(craft\web\Response))
  #22 /vendor/craftcms/cms/src/web/Response.php(286): yii\web\Response-&gt;prepare()
  #23 /vendor/yiisoft/yii2/web/Response.php(339): craft\web\Response-&gt;prepare()
  #24 /vendor/yiisoft/yii2/base/Application.php(390): yii\web\Response-&gt;send()
  #25 /www/index.php(32): yii\base\Application-&gt;run()
  #26 {main}
  </code></pre>
  <p>Craft CMS: 4.4.3
  Craft Commerce: 4.2.3
  PHP: 8.1.1</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-11-29T07:12:18.393Z
Comments.Text: After you migrate, do you ever try to clearing the cache?
Comments.UserDisplayName: aodihis
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-11-30T09:56:36.707Z
Comments.Text: nope. cleared the cache several times. This has no effect
Comments.UserDisplayName: KSPR
Tags: <migration><craft4><commerce4>
Title: getDiscountByCode(): Argument #1 ($code) must be of type string, null given
ThreadText: # getDiscountByCode(): Argument #1 ($code) must be of type string, null given
  
  (Asked by: username_0 on 2022-11-28)
  
  I migrated to craft 4 according to the migration guide and everything went well.
  Steps to reproduce
  
  1. Migrate to craft
  2. Add something into the cart
  3. On the Cart template there is the following error on the cart page:
  
  > craft\commerce\services\Discounts::getDiscountByCode(): Argument #1
  > ($code) must be of type string, null given, called in
  > /Users/atelierworkstation/Documents/git-local/atelier-shop/vendor/twig/twig/src/Extension/CoreExtension.php
  > on line 1607
  
  ```
  TypeError: craft\commerce\services\Discounts::getDiscountByCode(): Argument #1 ($code) must be of type string, null given, called in /vendor/twig/twig/src/Extension/CoreExtension.php on line 1607 and defined in /vendor/craftcms/commerce/src/services/Discounts.php:382
  Stack trace:
  #0 /vendor/twig/twig/src/Extension/CoreExtension.php(1607): craft\commerce\services\Discounts->getDiscountByCode(NULL)
  #1 /vendor/craftcms/cms/src/helpers/Template.php(110): twig_get_attribute(Object(craft\web\twig\Environment), Object(Twig\Source), Object(craft\commerce\services\Discounts), 'getDiscountByCo...', Array, 'method', false, false)
  #2 /storage/runtime/compiled_templates/48/4814239c41dedafc8391a1b70140a2d5.php(59): craft\helpers\Template::attribute(Object(craft\web\twig\Environment), Object(Twig\Source), Object(craft\commerce\services\Discounts), 'getDiscountByCo...', Array, 'method')
  #3 /vendor/twig/twig/src/Template.php(171): __TwigTemplate_fc9f511b5bd2fbee71b2e2d81933d7e6->block_main(Array, Array)
  #4 /storage/runtime/compiled_templates/1c/1c64b2042fe0dfe96716d9e6f05f4b31.php(332): Twig\Template->displayBlock('main', Array, Array)
  #5 /vendor/twig/twig/src/Template.php(171): __TwigTemplate_f939a9e67f563b6befd17836bf1b98ec->block_body(Array, Array)
  #6 /storage/runtime/compiled_templates/1c/1c64b2042fe0dfe96716d9e6f05f4b31.php(304): Twig\Template->displayBlock('body', Array, Array)
  #7 /vendor/twig/twig/src/Template.php(394): __TwigTemplate_f939a9e67f563b6befd17836bf1b98ec->doDisplay(Array, Array)
  #8 /vendor/twig/twig/src/Template.php(367): Twig\Template->displayWithErrorHandling(Array, Array)
  #9 /storage/runtime/compiled_templates/06/06430c5474c19a0e396cb203c104bc63.php(53): Twig\Template->display(Array, Array)
  #10 /vendor/twig/twig/src/Template.php(394): __TwigTemplate_f1d0c467d20bbb79bcf56d6786094c73->doDisplay(Array, Array)
  #11 /vendor/twig/twig/src/Template.php(367): Twig\Template->displayWithErrorHandling(Array, Array)
  #12 /storage/runtime/compiled_templates/48/4814239c41dedafc8391a1b70140a2d5.php(46): Twig\Template->display(Array, Array)
  #13 /vendor/twig/twig/src/Template.php(394): __TwigTemplate_fc9f511b5bd2fbee71b2e2d81933d7e6->doDisplay(Array, Array)
  #14 /vendor/twig/twig/src/Template.php(367): Twig\Template->displayWithErrorHandling(Array, Array)
  #15 /vendor/twig/twig/src/Template.php(379): Twig\Template->display(Array)
  #16 /vendor/twig/twig/src/TemplateWrapper.php(40): Twig\Template->render(Array, Array)
  #17 /vendor/twig/twig/src/Environment.php(277): Twig\TemplateWrapper->render(Array)
  #18 /vendor/craftcms/cms/src/web/View.php(451): Twig\Environment->render('purchase/cart', Array)
  #19 /vendor/craftcms/cms/src/web/View.php(504): craft\web\View->renderTemplate('purchase/cart', Array)
  #20 /vendor/craftcms/cms/src/web/TemplateResponseFormatter.php(56): craft\web\View->renderPageTemplate('purchase/cart', Array, 'site')
  #21 /vendor/yiisoft/yii2/web/Response.php(1098): craft\web\TemplateResponseFormatter->format(Object(craft\web\Response))
  #22 /vendor/craftcms/cms/src/web/Response.php(286): yii\web\Response->prepare()
  #23 /vendor/yiisoft/yii2/web/Response.php(339): craft\web\Response->prepare()
  #24 /vendor/yiisoft/yii2/base/Application.php(390): yii\web\Response->send()
  #25 /www/index.php(32): yii\base\Application->run()
  #26 {main}
  
  ```
  
  Craft CMS: 4.4.3
  Craft Commerce: 4.2.3
  PHP: 8.1.1
  
  **Tags:** migration, craft4, commerce4
  
  > **Comments:**
  > **username_1**: After you migrate, do you ever try to clearing the cache?  
  > **username_0**: nope. cleared the cache several times. This has no effect  
  
  ---
  
  ## 0 answers
  
  