In Administration / Server / Debugging Debug messages debug NONE: Do not show any errors or warningsMINIMAL: Show only fatal errorsNORMAL: Show errors, warnings and noticesALL: Show all reasonable PHP debug messagesDEVELOPER: extra Moodle debug messages for developers
which setting do you have?
If you set it to NONE or MINIMAL, you should no longer see these Notice messages which are only aimed at developers and do not prevent Moodle from working.
Can you check?
Joseph