Why is apache dtd for struts throwing errors

This morning several branches of a system I am working on all started to break with the following error messages:
(everything was fine last night)

 [37m2018-09-12 11:55:34.733[0;39m [1;31mERROR[0;39m [37m--- [           main]
 [0;39m [     ] 36mcom.opensymphony.xwork2.util.DomHelper  
 [0;39m : The markup declarations contained or pointed to by the document type declaration must be well-formed. at (-//Apache Software Foundation//DTD Struts Configuration 2.5//EN:1:3)
org.xml.sax.SAXParseException: The markup declarations contained or pointed to by the document type declaration must be well-formed.

The reference is in struts.xml which looks like the following:

<!DOCTYPE struts PUBLIC
 "-//Apache Software Foundation//DTD Struts 
  Configuration 2.5//EN"
 "http://struts.apache.org/dtds/struts-2.5.dtd">

Going to the above url i get this message:

This page contains the following errors:
error on line 35 at column 2: StartTag: invalid 
element name
Below is a rendering of the page up to the first 
error.

Since this just started happening across several branches, some of which have not had any changes to their struts.xml file, I am guessing this is an apache problem. Anyone else seeing this?