diff --git a/src/wp-includes/class-wp-term-query.php b/src/wp-includes/class-wp-term-query.php
index b7c3b42a2b..7431d1f5f0 100644
--- a/src/wp-includes/class-wp-term-query.php
+++ b/src/wp-includes/class-wp-term-query.php
@@ -678,7 +678,7 @@ class WP_Term_Query {
 		$cache        = wp_cache_get( $cache_key, 'terms' );
 		if ( false !== $cache ) {
 			if ( 'all' === $_fields ) {
-				$cache = array_map( 'get_term', $cache );
+				$cache = $this->populate_terms( $cache );
 			}
 
 			$this->terms = $cache;
@@ -810,7 +810,7 @@ class WP_Term_Query {
 		wp_cache_add( $cache_key, $terms, 'terms', DAY_IN_SECONDS );
 
 		if ( 'all' === $_fields || 'all_with_object_id' === $_fields ) {
-			$terms = array_map( 'get_term', $terms );
+			$terms = $this->populate_terms( $terms );
 		}
 
 		$this->terms = $terms;
@@ -972,4 +972,31 @@ class WP_Term_Query {
 
 		return $wpdb->prepare( '((t.name LIKE %s) OR (t.slug LIKE %s))', $like, $like );
 	}
+
+	/**
+	 * Creates an array of term objects from an array of term IDs.
+	 *
+	 * Also discards invalid term objects.
+	 *
+	 * @since 5.0.0
+	 *
+	 * @param array $term_ids Term IDs.
+	 * @return array
+	 */
+	protected function populate_terms( $term_ids ) {
+		$terms = array();
+
+		if ( ! is_array( $term_ids ) ) {
+			return $terms;
+		}
+
+		foreach ( $term_ids as $key => $term_id ) {
+			$term = get_term( $term_id );
+			if ( $term instanceof WP_Term ) {
+				$terms[ $key ] = $term;
+			}
+		}
+
+		return $terms;
+	}
 }
diff --git a/tests/phpunit/tests/term/query.php b/tests/phpunit/tests/term/query.php
index b517417f06..39496b16cb 100644
--- a/tests/phpunit/tests/term/query.php
+++ b/tests/phpunit/tests/term/query.php
@@ -614,4 +614,68 @@ class Tests_Term_Query extends WP_UnitTestCase {
 		);
 		$this->assertSame( array(), $q->terms );
 	}
+
+	/**
+	 * @ticket 42691
+	 */
+	public function test_null_term_object_should_be_discarded() {
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		$terms = self::factory()->term->create_many( 3, array(
+			'taxonomy' => 'wptests_tax',
+		) );
+
+		$this->term_id = $terms[1];
+
+		add_filter( 'get_term', array( $this, 'filter_term_to_null' ) );
+		$found = get_terms( array(
+			'taxonomy'   => 'wptests_tax',
+			'hide_empty' => false,
+		) );
+		remove_filter( 'get_term', array( $this, 'filter_term_to_null' ) );
+
+		$expected = array( $terms[0], $terms[2] );
+
+		$this->assertEqualSets( $expected, wp_list_pluck( $found, 'term_id' ) );
+	}
+
+	public function filter_term_to_null( $term ) {
+		if ( $this->term_id === $term->term_id ) {
+			return null;
+		}
+
+		return $term;
+	}
+
+	/**
+	 * @ticket 42691
+	 */
+	public function test_error_term_object_should_be_discarded() {
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		$terms = self::factory()->term->create_many( 3, array(
+			'taxonomy' => 'wptests_tax',
+		) );
+
+		$this->term_id = $terms[1];
+
+		add_filter( 'get_term', array( $this, 'filter_term_to_wp_error' ) );
+		$found = get_terms( array(
+			'taxonomy'   => 'wptests_tax',
+			'hide_empty' => false,
+		) );
+		remove_filter( 'get_term', array( $this, 'filter_term_to_wp_error' ) );
+
+		$expected = array( $terms[0], $terms[2] );
+
+		$this->assertEqualSets( $expected, wp_list_pluck( $found, 'term_id' ) );
+	}
+
+	public function filter_term_to_wp_error( $term ) {
+		if ( $this->term_id === $term->term_id ) {
+			return new WP_Error( 'foo' );
+		}
+
+		return $term;
+	}
 }