How to fix "sudo: unable to open ... Read-only file system"?

Question

The title might not be as descriptive as I would like it to be but couldn't come up with a better one.

My server's file system went into Read-only. And I don't understand why it does so and how to solve it.

I can SSH into the server and when trying to start apache2 for example I get the following :

username@srv1:~$ sudo service apache2 start
[sudo] password for username:
sudo: unable to open /var/lib/sudo/username/1: Read-only file system
 * Starting web server apache2                                                                                                                                                                                                               (30)Read-only file system: apache2: could not open error log file /var/log/apache2/error.log.
Unable to open logs
Action 'start' failed.
The Apache error log may have more information.

When I try restarting the server I get :

username@srv1:~$ sudo shutdown -r now
[sudo] password for username:
sudo: unable to open /var/lib/sudo/username/1: Read-only file system

Once I restart it manually it just start up without any warning or message saying something is wrong.

I hope somebody could point me into the right direction to resolve this issue.

Solution 1

The filesystem will usually go into read-only while the system is running if there is a filesystem consistency issue. This is specified in fstab as errors=remount-ro and will occur when a FS access fails or an emergency read-only remount is requested via Alt+SysRq+U. You can run:

sudo fsck -Af -M

to force a check of all filesystems. As one of the other answers states, looking at dmesg is also very helpful.

Edit: Don't forget the -M on the command-line.

NOTE: As mentioned by Bibhas in his answer: If fsck gets stuck after its version banner:

$ sudo fsck -Af -M
fsck from util-linux 2.20.1

you may want to try using the EXT4-specific fsck

$ sudo fsck.ext4 -f /dev/sda1

Provided the partition in question /dev/sda1 was an ext4 filesystem.

Solution 2

The answer by hexafraction didn't work for me. Every time I tried executing sudo fsck -Af -M it just showed

$ sudo fsck -Af -M
fsck from util-linux 2.20.1

and nothing else. No error or anything. For me, booting into a live disc and executing this worked -

sudo fsck.ext4 -f /dev/sda1

Provided the partition in question /dev/sda1 was an ext4 filesystem.

Solution 3

Here is the command that solved my problem :

mount -o remount /

better than a reboot or sudo fsck -Af

Solution 4

If you want to force your root filesystem to remount as rw, you can do the following.

mount -o remount,rw /

Solution 5

Try running dmesg | grep "EXT4-fs error" to see if you have any issues related to the filesystem / journaling system itself. I would recommend you to restart your system, then. Also, sudo fsck -Af answer by ObsessiveSSOℲ won't hurt.

View more solutions

Comments

[Forty-Two]

I recommend to @John to change the answer to the last posted answer by Bibhas as it actually works where the other answers are not helpful at all actually.

[Ciro Santilli OurBigBook.com]

For MicroSD: askubuntu.com/questions/213889/…

[vanduc1102]

Everyone, this question is for a server, not a PC. If you have this issue on your dual boot PC, Please check The **quick start** option can be found in **power options** in the control panel of Windows. I'm having the same issue with an Ubuntu on AWS

[Parisa.H.R]

I have this problem too, and non of solutions work fo me i use ubuntu 18.04 , and i don't know what makes this happened , I should restart my system and then it show me page that contain (initramfs) there when I run fsck /dev/sda1 -y and reboot os work and again after 30 minutes to 1 hour problem happens.

[Admin]

if disk is NTFS and used by Windows - run from it shutdown /f /r /t 0, it helped for me

[Drew Noakes]

Not better if the OS made your disk read-only to prevent possible corruption.

[isomorphismes]

What should one look at / grep for in dmesg output?

[gertvdijk]

I think you should not force a filesystem check on other r/w mounted filesystems. That will potentially corrupt your data. Add the -M option to skip mounted filesystems. (-M Do not check mounted filesystems and return an exit code of 0 for mounted filesystems. from FSCK(8))

[Nathan Osman]

Not only that - only root will be able to remount the filesystem and sudo isn't going to work if the filesystem is read-only.

[Nathan Osman]

Unfortunately if you opted to encrypt your home folder, dmesg is bound to be full of useless errors from ecryptfs.

[Mark Kramer]

This doesn't help, I just get the same error when trying to run that command. sudo: unable to open /var/lib/sudo/kuplack/1: Read-only file system fsck from util-linux 2.20.1

[Mark Kramer]

Doesn't help, I just get the same message: sudo: unable to open /var/lib/sudo/kuplack/1: Read-only file system mount: cannot remount block device /dev/sda2 read-write, is write-protected

[Forty-Two]

Thank you for this answer. This is the only thing that had actually worked

[naught101]

But... -M will skip mounted file systems, including /dev/sda1 (or what ever mounted drive includes /var/lib/sudo/... ). @MarkKramer: I highly recommend always setting the root password when installing linux, with sudo su; passwd. Then you can use su -c fsck -Af -M.

[dalore]

-M means not to do mounted filesystems. Your filesystem /dev/sda1 was mounted (I'm guessing at /). So it was skipped.

[R T]

o yes this one worked.

[David Foerster]

Welcome to Ask Ubuntu! I recommend editing this answer to expand it with specific details about how to do this. (See also How do I write a good answer? for general advice about what sorts of answers are considered most valuable on Ask Ubuntu.)

[FreeSoftwareServers]

Yea for me I needed to remove -M since /dev/sda1 was mounted, and to make your life easier, add -Afy (The y means answer yes to all prompts)... I play fast and loose with VM's so I'm usually ok with this type of solution, but if this is unbacked up hardware, might take a different approach and read dmesg.

[efkan]

sudo fsck.ext4 -f /dev/sda1 works. Still a restart needs.

[Darshan Chaudhary]

running fsck on a mounted filesystem is not a good idea

[nanofarad]

@DarshanChaudhary The -M flag causes fsck to skip mounted filesystems. See the fsck (8) manpage.

[Sinan Gül]

command succeed after reboot the system.

[Eduardo Lucio]

UP! For -> "The filesystem will usually go into read-only while the system is running if there is a filesystem consistency issue."

[Rosário Pereira Fernandes]

It worked for me on ubuntu 16.04.3 Thank you

[nomen]

I am fairly certain this is happening to me right now, given that my computer told me it forgot its time this morning.

[Rishabh Agrahari]

mount: cannot remount /dev/sda8 read-write, is write-protected

[Fathur Rohim]

this was solved my problem, I use hetzner cloud with 160gb ssd, never had such error before

[birdman]

This answer does not work for me. After executing the suggested command I receive fsck from util-linux 2.29.2

[Blairg23]

This actually did end up corrupting my filesystem :(

[NelsonGon]

Only one that worked. At the cost of startup speed.

[Pranav]

@hexafraction many humans don't have "SysRq" keyboard buttom in their laptop keyboard, I am one of them. How do I pull this off?

[nanofarad]

@PrabeshBhattarai SysRq is the same (physical) key as PrintScreen, even if your laptop manufacturer didn't physically print "SysRq" on it; alternatively you may need Fn+[something]. That said, you don't need to press that key combination; I mention that keyboard shortcut as an example of something that can cause a filesystem to fail read-only, not as a step that you need to take.

[ScottyBlades]

sudo fsck -Af -M gives me: fsck: illegal option -- A fsck: ? option?

[ScottyBlades]

fsck from util-linux 2.20.1 gives me: fsck usage: fsck [-fdnypqL] [-l number]

[ScottyBlades]

sudo fsck.ext4 -f /dev/sda1 gives me: sudo: fsck.ext4: command not found

[ScottyBlades]

mount_apfs: unrecognized option 'remount'

[nanofarad]

@ScottyBlades This answer is seven years old, and the flags have likely changed--I don;t have a copy of fsck from util-linux 2.20.1, and my copy handles -A just fine, so I don't have any great advice, aside from manually invoking on each volume that needs to be checked.

[ScottyBlades]

@hexafraction, it's cool. I'm new to web dev. So I think I'm making more obvious/basic mistakes that would go under most seasoned developer's radars. MY SOLUTION: When I clicked "save as" I was saving to the root directory, not the directory I actually wanted to save in. Making sure I saved to the correct location solved the problem.

[nanofarad]

@ScottyBlades Understood. Looks like your situation was mostly unrelated to actual file system corruption then, meaning that there was no need to get fsck involved.

[ScottyBlades]

@hexafraction, good to know

[Farid Chowdhury]

Awesome brother 💪

[Forty3]

Here we are, 2020, and this saved my Ubuntu laptop. Thanks @Bibhas!

[Salem F]

Im on virtual machine (KVM VPS) and I got this error mount: /: cannot remount /dev/mapper/vg_jh-root read-write, is write-protected.

[Coconut]

If someone needs to remount the disk in read/write mode, try this: $ sudo mount -vo remount,rw /

[Òscar Raya]

TY, I had a problem with snappy daemon and tryied a lots of things. Your sudo fsck.ext4 -f /dev/sda1 saved me (in my case on sda2).

[Muhammad bin Yusrat]

Thanks! This worked! :)

[Heisenberg]

Didn't worked but I think windows is causing this issue

[Sarato]

This worked for me, when my off-brand mp3 player switched to "read-only" all of a sudden

[Bhuwan Adhikari]

this was kind of similar for me too.

[Yinon_90]

I solve my issue in a similar way, I posted here: askubuntu.com/a/1346172/1330220

[Mark E]

¡CAUTION! I was fixing a remote server and it didn't turn on after reboot which made things way harder, I recommend testing other solutions before trying to rebbot specially if you're not physically with the computer. For the first time in the engineering world, turning it off and on again was a big problem instead of a solution :(

[flm]

I get mount: /: cannot remount /dev/sda2 read-write, is write-protected.

[Aleks]

Oh, this is perfect.

[Zaman Oof]

@MarkE Rebooting Against Availability so should be the latest solution

[lightonphiri]

Thank you for this: I urgently need to pull files from my problematic installation and this helped tremendously! Incidentally, I ran fsck.ext4 via my "(Initramfs)" shell and it worked perfectly!

[kyriakosSt]

This answer should have more upvotes. It is the most failsafe option, that requires far less understanding from the user. Thank you.

[Fathy]

this solved my problem i remount the partition only aka sudo mount -o remount, rw 0A4819AC48393