/etc/fstab still had entries that corresponded to old partitions that I had deleted. To fix this, I simply commented them out.
If you're dealing with a UUID mismatch, use "sudo vol_id <the partition>" to figure out the correct UUID for each partition, so that you can overwrite the incorrect UUIDs in fstab.
I was able to resolve this problem.
/etc/fstab still had entries that corresponded to old partitions that I had deleted. To fix this, I simply commented them out.
If you're dealing with a UUID mismatch, use "sudo vol_id <the partition>" to figure out the correct UUID for each partition, so that you can overwrite the incorrect UUIDs in fstab.