diff --git a/core/tests/Drupal/FunctionalTests/AssertLegacyTrait.php b/core/tests/Drupal/FunctionalTests/AssertLegacyTrait.php
index 5785a7d8c894..6ca9f850a235 100644
--- a/core/tests/Drupal/FunctionalTests/AssertLegacyTrait.php
+++ b/core/tests/Drupal/FunctionalTests/AssertLegacyTrait.php
@@ -93,58 +93,6 @@ trait AssertLegacyTrait {
     }
   }
 
-  /**
-   * Passes if the text is found ONLY ONCE on the text version of the page.
-   *
-   * The text version is the equivalent of what a user would see when viewing
-   * through a web browser. In other words the HTML has been filtered out of
-   * the contents.
-   *
-   * @param string|\Drupal\Component\Render\MarkupInterface $text
-   *   Plain text to look for.
-   * @param string $message
-   *   (optional) A message to display with the assertion. Do not translate
-   *   messages with t(). If left blank, a default message will be displayed.
-   *
-   * @deprecated Scheduled for removal in Drupal 9.0.0.
-   *   Use $this->getSession()->getPage()->getText() and substr_count() instead.
-   */
-  protected function assertUniqueText($text, $message = NULL) {
-    // Cast MarkupInterface objects to string.
-    $text = (string) $text;
-
-    $message = $message ?: "'$text' found only once on the page";
-    $page_text = $this->getSession()->getPage()->getText();
-    $nr_found = substr_count($page_text, $text);
-    $this->assertSame(1, $nr_found, $message);
-  }
-
-  /**
-   * Passes if the text is found MORE THAN ONCE on the text version of the page.
-   *
-   * The text version is the equivalent of what a user would see when viewing
-   * through a web browser. In other words the HTML has been filtered out of
-   * the contents.
-   *
-   * @param string|\Drupal\Component\Render\MarkupInterface $text
-   *   Plain text to look for.
-   * @param string $message
-   *   (optional) A message to display with the assertion. Do not translate
-   *   messages with t(). If left blank, a default message will be displayed.
-   *
-   * @deprecated Scheduled for removal in Drupal 9.0.0.
-   *   Use $this->getSession()->getPage()->getText() and substr_count() instead.
-   */
-  protected function assertNoUniqueText($text, $message = '') {
-    // Cast MarkupInterface objects to string.
-    $text = (string) $text;
-
-    $message = $message ?: "'$text' found more than once on the page";
-    $page_text = $this->getSession()->getPage()->getText();
-    $nr_found = substr_count($page_text, $text);
-    $this->assertGreaterThan(1, $nr_found, $message);
-  }
-
   /**
    * Asserts the page responds with the specified response code.
    *
@@ -180,27 +128,6 @@ trait AssertLegacyTrait {
     }
   }
 
-  /**
-   * Asserts that a field exists with the given name and value.
-   *
-   * @param string $name
-   *   Name of field to assert.
-   * @param string $value
-   *   (optional) Value of the field to assert. You may pass in NULL (default)
-   *   to skip checking the actual value, while still checking that the field
-   *   exists.
-   *
-   * @deprecated Scheduled for removal in Drupal 9.0.0.
-   *   Use $this->assertSession()->fieldNotExists() or
-   *   $this->assertSession()->fieldValueNotEquals() instead.
-   */
-  protected function assertNoFieldByName($name, $value = NULL) {
-    $this->assertSession()->fieldNotExists($name);
-    if ($value !== NULL) {
-      $this->assertSession()->fieldValueNotEquals($name, (string) $value);
-    }
-  }
-
   /**
    * Asserts that a field exists with the given ID and value.
    *
@@ -416,53 +343,6 @@ trait AssertLegacyTrait {
     return $this->assertSession()->optionNotExists($id, $option);
   }
 
-  /**
-   * Asserts that a select option in the current page is checked.
-   *
-   * @param string $id
-   *   ID of select field to assert.
-   * @param string $option
-   *   Option to assert.
-   * @param string $message
-   *   (optional) A message to display with the assertion. Do not translate
-   *   messages with t(). If left blank, a default message will be displayed.
-   *
-   * @deprecated Scheduled for removal in Drupal 9.0.0.
-   *   Use $this->assertSession()->optionExists() instead and check the
-   *   "selected" attribute yourself.
-   */
-  protected function assertOptionSelected($id, $option, $message = NULL) {
-    $option_field = $this->assertSession()->optionExists($id, $option);
-    $message = $message ?: "Option $option for field $id is selected.";
-    $this->assertTrue($option_field->hasAttribute('selected'), $message);
-  }
-
-  /**
-   * Asserts that a checkbox field in the current page is checked.
-   *
-   * @param string $id
-   *   ID of field to assert.
-   *
-   * @deprecated Scheduled for removal in Drupal 9.0.0.
-   *   Use $this->assertSession()->checkboxChecked() instead.
-   */
-  protected function assertFieldChecked($id) {
-    $this->assertSession()->checkboxChecked($id);
-  }
-
-  /**
-   * Asserts that a checkbox field in the current page is not checked.
-   *
-   * @param string $id
-   *   ID of field to assert.
-   *
-   * @deprecated Scheduled for removal in Drupal 9.0.0.
-   *   Use $this->assertSession()->checkboxNotChecked() instead.
-   */
-  protected function assertNoFieldChecked($id) {
-    $this->assertSession()->checkboxNotChecked($id);
-  }
-
   /**
    * Passes if the raw text IS found escaped on the loaded page, fail otherwise.
    *
@@ -493,19 +373,6 @@ trait AssertLegacyTrait {
     $this->assertSession()->assertNoEscaped($raw);
   }
 
-  /**
-   * Triggers a pass if the Perl regex pattern is found in the raw content.
-   *
-   * @param string $pattern
-   *   Perl regex to look for including the regex delimiters.
-   *
-   * @deprecated Scheduled for removal in Drupal 9.0.0.
-   *   Use $this->assertSession()->responseMatches() instead.
-   */
-  protected function assertPattern($pattern) {
-    $this->assertSession()->responseMatches($pattern);
-  }
-
   /**
    * Asserts whether an expected cache tag was present in the last response.
    *