diff --git src/bp-core/bp-core-avatars.php src/bp-core/bp-core-avatars.php
index 8f264f607..18f9040ea 100644
--- src/bp-core/bp-core-avatars.php
+++ src/bp-core/bp-core-avatars.php
@@ -456,7 +456,9 @@ function bp_core_fetch_avatar( $args = '' ) {
 
 	// Use an alias to leave the param unchanged.
 	$avatar_classes = $params['class'];
-	if ( ! is_array( $avatar_classes ) ) {
+	if ( is_null( $avatar_classes ) ) {
+		$avatar_classes = array();
+	} elseif ( ! is_array( $avatar_classes ) ) {
 		$avatar_classes = explode( ' ', $avatar_classes );
 	}
 
diff --git src/bp-core/classes/class-bp-core-bp-nav-backcompat.php src/bp-core/classes/class-bp-core-bp-nav-backcompat.php
index cf9c2b4df..ff9e874d3 100644
--- src/bp-core/classes/class-bp-core-bp-nav-backcompat.php
+++ src/bp-core/classes/class-bp-core-bp-nav-backcompat.php
@@ -60,6 +60,7 @@ class BP_Core_BP_Nav_BackCompat implements ArrayAccess {
 	 * @param mixed $offset Array offset.
 	 * @param array $value  Nav item.
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetSet( $offset, $value ) {
 		_doing_it_wrong(
 			'bp_nav',
@@ -94,6 +95,7 @@ class BP_Core_BP_Nav_BackCompat implements ArrayAccess {
 	 * @param mixed $offset Array offset.
 	 * @return BP_Core_BP_Nav_BackCompat
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetGet( $offset ) {
 		_doing_it_wrong(
 			'bp_nav',
@@ -101,12 +103,10 @@ class BP_Core_BP_Nav_BackCompat implements ArrayAccess {
 			'2.6.0'
 		);
 
-//		if ( ! isset( $this->backcompat_nav[ $offset ] ) ) {
-			$nav = $this->get_nav( $offset );
-			if ( $nav && isset( $nav[ $offset ] ) ) {
-				$this->backcompat_nav[ $offset ] = new self( $nav[ $offset ] );
-			}
-//		}
+		$nav = $this->get_nav( $offset );
+		if ( $nav && isset( $nav[ $offset ] ) ) {
+			$this->backcompat_nav[ $offset ] = new self( $nav[ $offset ] );
+		}
 
 		return $this->backcompat_nav[ $offset ];
 	}
@@ -119,6 +119,7 @@ class BP_Core_BP_Nav_BackCompat implements ArrayAccess {
 	 * @param mixed $offset Array offset.
 	 * @return bool
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetExists( $offset ) {
 		_doing_it_wrong(
 			'bp_nav',
@@ -145,6 +146,7 @@ class BP_Core_BP_Nav_BackCompat implements ArrayAccess {
 	 *
 	 * @param mixed $offset Array offset.
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetUnset( $offset ) {
 		_doing_it_wrong(
 			'bp_nav',