I encountered this error on my Ubuntu machine:
The root filesystem on /dev/sda1 requires a manual fsck
I launched the command
fsck -fy /dev/sda1
and the system has done operations on the filesystem but at the end of the procedure the system does not start but remains on the following screen:
/dev/sda1: THE FILE SYSTEM WAS MODIFIED
/dev/sda1: 603235/6373376 (0.2% not contiguous), ...
....
Pass 1: Checking inodes, blocks and sizes
...
Pass 5: Checking group summary information
(initramfs)
How can I start the system?