@Joulinar However, by quickly looking on Google, it seems it is normal to see that error and you cannot really do much about it
- https://wiki.opennms.org/wiki/SNMP_spams_my_log (end of the page)
@Joulinar I think I solved the problem. With the function of dietpi drive manager I tried to see if I could delete this /mnt/batocera as I never created/used it. As soon as I opened the drive manager the partition disappeared. I guess for some reason the system was thinking that partition was existing and freezing when not finding it but now it looks like the registry was automatically "fixed" after accessing the drive manager. Still don't know how all this mess created but I am happy got solved.