I tried to resize an ext4 partition today (unmounted via gparted gui). However, the initial e2fsck failed before gparted even attempted to resize the partition. The error message read "/dev/sdb1: no such file or directory". (Didn't save a log, though.)

Running a check on the partition from within gparted and retrying the operation did not help. (The check didn't report any errors.)

What did fix it was running

sudo fsck.ext4 -v /dev/sdb1

from the shell, which came up with no apparent errors:

e2fsck 1.42.13 (17-May-2015)
/dev/sdb1: clean, 806434/12214272 files, 13810992/48827880 blocks

After that, however, the resize operation went through smoothly.

What puzzles me is that, since I ran just a basic fsck.ext4, gparted's check option should have done all of this (and possibly more). Apparently the check operation doesn't cover all it should. I can only guess why – maybe f2fsck mis-recognizes the file system as an earlier version (ext3 or ext2) and runs an incorrect version for the check, but the whatever runs prior to the resize operation still considers the file system to be faulty.