Before getting this "invalid partition table!" warning, I successfully installed Debian and Ubuntu side by side. No problem, no boot warning, no mess with grub, everything ok. But yesterday I decided to downsize my Debian partition (/dev/sda1) in order to make some free space for a new one.
I used Gparted for this job and at first glance everything was fine, except this "invalid partition table!" warning right before the grub screen. Moreover I noticed a warning in the output of fdisk
which tells that partition 4 has a problem, but I can't see this partition in GParted.
I'm looking for some clarifications about the meaning of this warning. I've found nothing that fits with my problem on the web. I'm stuck and confused currently, after several hours of searching, I feel like I didn't learn anything more...