Hello, I can make changes now to the template, but changing content site modules, I get the same error An error has occurred. 0 Undefined constant "DS"
Thanks in advance Nicolas
..it looks like the problem occurs only with the Image Show GK4 module.
Kindly check your old topic, I put the solution there:
https://www.joomlart.com/forums/d/39079-an-error-has-occurred-0-undefined-constant-ds/5
I updated 3 files in this folder of module: /modules/mod_image_show_gk4/admin/elements/
config.php slidemanager.php styles.php
Thanks! Solved!