I remove all esp8266 files from arduino15 folder and load from boards manager the esp8266 byy esp8266 community version 2.5.2 and everything works fine.
As many times as i tried to upadate the boards to version 2.6.0 i get the same error that it is in my first post.
I will stay with this version till they fix it.
Thanks for your help.
Yannis