Index: wp-includes/class-wp-xmlrpc-server.php
===================================================================
--- wp-includes/class-wp-xmlrpc-server.php	(revision 39258)
+++ wp-includes/class-wp-xmlrpc-server.php	(working copy)
@@ -2142,7 +2142,7 @@
 			return new IXR_Error( 404, __( 'Invalid term ID.' ) );
 
 		if ( ! current_user_can( 'assign_term', $term_id ) ) {
-			return new IXR_Error( 401, __( 'Sorry, you are not allowed to assign this term.' ) );
+			return new IXR_Error( 401, __( 'Sorry, you are not allowed to assign terms.' ) );
 		}
 
 		return $this->_prepare_term( $term );
Index: wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
===================================================================
--- wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php	(revision 39258)
+++ wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php	(working copy)
@@ -462,7 +462,7 @@
 		}
 
 		if ( ! $this->check_assign_terms_permission( $request ) ) {
-			return new WP_Error( 'rest_cannot_assign_term', __( 'Sorry, you are not allowed to assign the provided terms.' ), array( 'status' => rest_authorization_required_code() ) );
+			return new WP_Error( 'rest_cannot_assign_term', __( 'Sorry, you are not allowed to assign terms.' ), array( 'status' => rest_authorization_required_code() ) );
 		}
 
 		return true;
@@ -599,7 +599,7 @@
 		}
 
 		if ( ! $this->check_assign_terms_permission( $request ) ) {
-			return new WP_Error( 'rest_cannot_assign_term', __( 'Sorry, you are not allowed to assign the provided terms.' ), array( 'status' => rest_authorization_required_code() ) );
+			return new WP_Error( 'rest_cannot_assign_term', __( 'Sorry, you are not allowed to assign terms.' ), array( 'status' => rest_authorization_required_code() ) );
 		}
 
 		return true;