Index: src/includes/common/template.php
--- src/includes/common/template.php
+++ src/includes/common/template.php
@@ -2151,7 +2151,7 @@
  *
  * @return bool True if match, false if not
  */
-function bbp_is_query_name( $name = '' )  {
+function bbp_is_query_name( $name = '' ) {
 	return (bool) ( bbp_get_query_name() === $name );
 }

@@ -2162,7 +2162,7 @@
  *
  * @return string To return the query var value
  */
-function bbp_get_query_name()  {
+function bbp_get_query_name() {
 	return get_query_var( '_bbp_query_name' );
 }

@@ -2173,7 +2173,7 @@
  *
  * @param string $name What to set the query var to
  */
-function bbp_set_query_name( $name = '' )  {
+function bbp_set_query_name( $name = '' ) {
 	set_query_var( '_bbp_query_name', $name );
 }

Index: src/includes/extend/buddypress/activity.php
--- src/includes/extend/buddypress/activity.php
+++ src/includes/extend/buddypress/activity.php
@@ -384,7 +384,7 @@
 		}

 		// User link for topic author
-		$user_link = bbp_get_user_profile_link( $user_id  );
+		$user_link = bbp_get_user_profile_link( $user_id );

 		// Topic
 		$topic_permalink = bbp_get_topic_permalink( $topic_id );
@@ -519,7 +519,7 @@
 		}

 		// Setup links for activity stream
-		$user_link = bbp_get_user_profile_link( $user_id  );
+		$user_link = bbp_get_user_profile_link( $user_id );

 		// Reply
 		$reply_url     = bbp_get_reply_url( $reply_id );
Index: src/includes/users/template.php
--- src/includes/users/template.php
+++ src/includes/users/template.php
@@ -444,11 +444,27 @@
 			return false;
 		}

-		$user      = get_userdata( $user_id );
-		$user_link = '<a href="' . esc_url( bbp_get_user_profile_url( $user_id ) ) . '">' . esc_html( $user->display_name ) . '</a>';
+		// Get the user
+		$user = get_userdata( $user_id );
+		if ( empty( $user ) ) {
+			return false;
+		}

+		// Display Name
+		$name = ! empty( $user->display_name )
+			? $user->display_name
+			: bbp_get_fallback_display_name();
+
+		// URL
+		$url = bbp_get_user_profile_url( $user_id );
+
+		// Link
+		$link = ! empty( $url )
+			? '<a href="' . esc_url( $url ) . '">' . esc_html( $name ) . '</a>'
+			: esc_html( $name );
+
 		// Filter & return
-		return apply_filters( 'bbp_get_user_profile_link', $user_link, $user_id );
+		return (string) apply_filters( 'bbp_get_user_profile_link', $link, $user_id );
 	}

 /**
@@ -596,11 +612,27 @@
 			return false;
 		}

-		$user      = get_userdata( $user_id );
-		$edit_link = '<a href="' . esc_url( bbp_get_user_profile_edit_url( $user_id ) ) . '">' . esc_html( $user->display_name ) . '</a>';
+		// Get the user
+		$user = get_userdata( $user_id );
+		if ( empty( $user ) ) {
+			return false;
+		}

+		// Display Name
+		$name = ! empty( $user->display_name )
+			? $user->display_name
+			: bbp_get_fallback_display_name();
+
+		// URL
+		$url = bbp_get_user_profile_edit_url( $user_id );
+
+		// Link
+		$link = ! empty( $url )
+			? '<a href="' . esc_url( $url ) . '">' . esc_html( $name ) . '</a>'
+			: esc_html( $name );
+
 		// Filter & return
-		return apply_filters( 'bbp_get_user_profile_edit_link', $edit_link, $user_id );
+		return (string) apply_filters( 'bbp_get_user_profile_edit_link', $link, $user_id );
 	}

 /**