Do you have the following in File, Additional Boards Manager urls: ?
http://arduino.esp8266.com/stable/package_esp8266com_index.json
If you have this and only this, i.e. without the staging directory, then you should be on 2.3.0 i.e. the last stable release.
Another thing to try is set your board to Generic ESP8266 in the Arduino IDE. We normally use this rather than WeMos as we develop for different ESP’s.
Then maybe track down your EEPROM.h and see if it looks like this:
/*
EEPROM.cpp - esp8266 EEPROM emulation
Copyright (c) 2014 Ivan Grokhotkov. All rights reserved.
This file is part of the esp8266 core for Arduino environment.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef EEPROM_h
#define EEPROM_h
#include <stddef.h>
#include <stdint.h>
#include <string.h>
class EEPROMClass {
public:
EEPROMClass(uint32_t sector);
void begin(size_t size);
uint8_t read(int address);
void write(int address, uint8_t val);
bool commit();
void end();
uint8_t * getDataPtr();
template<typename T>
T &get(int address, T &t) {
if (address < 0 || address + sizeof(T) > _size)
return t;
memcpy((uint8_t*) &t, _data + address, sizeof(T));
return t;
}
template<typename T>
const T &put(int address, const T &t) {
if (address < 0 || address + sizeof(T) > _size)
return t;
memcpy(_data + address, (const uint8_t*) &t, sizeof(T));
_dirty = true;
return t;
}
protected:
uint32_t _sector;
uint8_t* _data;
size_t _size;
bool _dirty;
};
extern EEPROMClass EEPROM;
#endif
This is not the latest version at https://github.com/esp8266/Arduino/blob/master/libraries/EEPROM/EEPROM.h but I think that is because there was a commit in August 2016 that is not included in the stable branch dated June 2016.
The location on my machine for the header, which also confirms the core of 2.3.0, for a Windows machine is at:
C:\Users\costas\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0\libraries\EEPROM
If you are on Windows just change costas in the path to your Windows username.