Thanks for the reply Angeles,
Sorry, I probably didn't express well what I meant. We are interested in knowing why your upgrade process triggered that error; before that fatal error, Moodle probably triggered other errors, but these other errors are only displayed in your browser when you have these 2 lines in your config.php, so I was asking if you could please run again the upgrade process, setting these 2 lines in your config.php before starting the upgrade from 2.9 to 3.0, and without applying the patch that fixes the issue. The idea is to reproduce the same fatal error you got plus other "debugging" messages, we need these "possible" debugging messages to know why is failing for you. If you don't want to paste sensitive info in here and it is fine for you, feel free to send it to davidm@moodle.com.
Reply in Spanish:
Ningun problema, yo tambien soy desastrillo en ingles Hasta ahora solo hemos podido reproducir tu error con una configuracion diferente a la tuya, y necesitamos saber mas para poder identificar bien el problema porque durante estos meses hemos actualizado muchas veces usando el navegador y no habiamos detectado este problema, si lo identificamos podremos ayudar a otra gente que seguramente le pasara lo mismo. Te pedia si podrias volver a actualizar de 2.9 a 3.0 (no en produccion claro) sin el parche que soluciona el problema, para reproducir el mismo fatal error que veias, pero anadiendo esas dos lineas a tu config.php (antes del require_once al fichero setup.php que esta al final) antes de ejecutar el upgrade. Si no puedes pegar aqui informacion sensible por ser un sitio publico puedes enviarme a mi lo que sea a davidm@moodle.com