ESP8266 compilation error: "previous declaration of 'HTTPMethod HTTP_HEAD'" I have an ESP8266 program that used to work but is now failing to compile with this error: 

C:\...\Arduino\libraries\WiFiManager/WiFiManager.h:25:24: note: in expansion of macro 'PROGMEM'

 const char HTTP_HEAD[] PROGMEM            = "&lt;!DOCTYPE html&gt;&lt;html lang=\"en\"&gt;&lt;head&gt;&lt;meta name=\"viewport\" content=\"width=device-width, initial-scale=1, user-scalable=no\"/&gt;&lt;title&gt;{v}&lt;/title&gt;";

                        ^

In file included from C:\...\MyEsp.ino:14:0:

C:\...AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.6.3\libraries\ESP8266WebServer\src/ESP8266WebServer.h:33:39: error: previous declaration of 'HTTPMethod HTTP_HEAD'

 enum HTTPMethod { HTTP_ANY, HTTP_GET, HTTP_HEAD, HTTP_POST, HTTP_PUT, HTTP_PATCH, HTTP_DELETE, HTTP_OPTIONS };
                                   ^


I don't recall changing anything, except maybe updating some libraries. Any ideas what could be causing this?  Here are my includes from the ESP8266 program:

#include &lt;Arduino.h&gt;

#include &lt;ESP8266WiFi.h&gt;
#include &lt;ESP8266WiFiMulti.h&gt;
#include &lt;ESP8266HTTPClient.h&gt;
#include &lt;WiFiClient.h&gt;

#include &lt;DNSServer.h&gt;            //Local DNS Server used for redirecting all requests to the configuration portal
#include &lt;ESP8266WebServer.h&gt;     //Local WebServer used to serve the configuration portal
#include &lt;WiFiManager.h&gt;          //https://github.com/tzapu/WiFiManager WiFi Configuration Magic

#define SERIAL_BUFFER_SIZE 256
You need a newer version of the WiFiManager.h library. This issue was fixed August last year.