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Cyclic Redundancy Check: what is it, and how do I get rid of it on my newly burnt CDs and DVDs?

When I burn a CD or DVD, I frequently get a “Cyclic Redundancy Check” error
when I go to read it. The media has no scratches or anything obviously wrong,
so why is this happening? And more importantly, what do I do?

A “Cyclic Redundancy Check”, or more commonly just “CRC”, is an error
detection mechanism that makes sure that the data you’re trying to read from
media, such as hard disks, CDs and DVDs, is actually correct. By “correct”, we
mean that the data you read is in fact the data that was written.

When a CRC check fails, there are several possibilities and places to

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A CRC works by taking a block of the data that is about to be written to the
media, calculating a checksum (basically some math involving all the data, that
results in a number), and writing that number, along with the original data, to
the media. When the data is later read, that same calculation happens, and if a
different number results, then an error is declared – the data read was not the
same as the data written.

CRC checks happen each time you read the media. Many CD and DVD burning
programs will include a read pass immediately after writing, to ensure that the
data was written properly.

There are several ways that a checksum error could happen:

  • A Bad Write: if the device that wrote the media had a
    problem while writing, it could have written the wrong data.

  • Dirt in the Writer: dust or other obstructions in a CD or
    DVD writer can interfere with the laser and cause the bad data to be written.

  • Bad Media: poor quality media, particularly CDs and DVDs,
    can sometimes “not take” the data that’s written to them. Perhaps there’s a
    flaw in the physical media. These types of flaws may not be visible to the
    naked eye – even a one-bit error can cause a CRC calculation to fail.

  • Bad Write Alignment: it’s fairly obvious that on CDs and
    DVDs data is written in a circle on the media. However, exactly where that
    circle lands is dependent on the alignment of the drive. It could be slightly
    off-center, or skewed in some way. This is frequently the case if a CD or DVD
    reads perfectly on the drive that wrote it, but fails when read on other

  • Scratches and Other Damage: you’ve mentioned that your
    media’s not scratched, so this may not apply to you, but CRC checking is most
    commonly thought of as a way to detect errors that result from physical damage
    to the media after it’s been written. And once again, remember that a tiny
    scratch, if in the wrong place, can do damage. If your problem is with multiple
    CDs or DVDs and you’ve been handling them properly, then it’s unlikely that
    this is the case.

  • Dirt in the Reader: much like dirt in the writer, dust and
    other particles can interfere with a CD or DVD reader’s ability to read the
    media properly.

  • Bad Read Alignment: again, much like bad write alignment,
    if the reader isn’t tracking to the same “circle”, it may not be able to read
    the data. Some drives are better at compensating for this than others.

  • Bad Reading Drive: finally, it’s always possible that the
    CD or DVD drive itself is having a problem reading in general.

“If you have a CD or DVD that is reporting a CRC error,
try reading it on different drives.”

As you can see, there are lots of possibilities.

If the problem “travels” with the CD or DVD you’ve written … meaning that
it fails when read in several different devices, then the problem is most
likely with the writer or the media itself.

If the problem happens only when read on one specific reader, then that
reader, and not the writer or media, is most suspect.

Make sure that you’re using high quality, brand name blank CDs and DVDs.
Occasionally clean the inside of your computer, including carefully vacuuming
the CD or DVD tray from the outside to remove excess dust. If there is an
alignment problem, there’s little you can do yourself – you’ll need to use
another drive.

Can bad data be “fixed”? – in a nutshell, no. I’ve actually
oversimplified the role of a CRC above. It typically includes both error
detection and correction. That means that the calculated checksum can
often also be used to determine what data is wrong, and return the correct data
instead, on the fly. This probably happens often, and you’d never notice. By
the time a CRC error has been declared, enough errors have occurred that the
error correction has failed. At that point, you’re pretty much out of luck.

If you have a CD or DVD that is reporting a CRC error, try reading it on
different drives. As I mentioned above, the ability of drives to compensate for
things like alignment problems, or “weak” writes, varies, and what’s unreadable
on one might be readable on another. If you do find a drive that
works, copy the data off immediately, and plan on burning it to a new CD or DVD
on a writer that’s known to be good.

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31 comments on “Cyclic Redundancy Check: what is it, and how do I get rid of it on my newly burnt CDs and DVDs?”

  1. Hi Leo…

    Nice site… and let me put this to you to continue this thread about CRC:

    I’ve just got a new laptop from Dell… it has XP Prof SP2, up to now I’ve been using XP Home SP1 (deliberately did not “up”grade to SP2).
    Many files which are on DVD which I need to copy over are being rejected by the new machine’s drive… back at the old machine they are accepted fine… but when I run CDcheck on the old machine errors are indeed flagged. Is there sthg about XP Prof (SP2) which would account for this… and more importantly, is there not some way of tweaking XP Prof SP2 so that it is less puritanical?

    Otherwise presumably I’ll have to reformat, install XP Home SP1 on the new machine and struggle to stop Micro$oft inflicting its hateful “up”grades on me and causing me even more Micro$oft-related stre$$… than normal?


  2. You might mention that you can also get a CRC error on SD cards… and various other media…. not only CDs/DVDs.

  3. The only answer I know of for the CRC error, is to download and use CDCheck on the CD or DVD. It reads and re-writes the whole CD/DVD, to a new folder, until it gets to the problem area. Then, it reads it, sector by sector, and stamps a “0” in an unreadable sector, until it finishes reading the “BAD” part of the CD/DVD and repairing it that way. This works for scratches and other errors on the CD/DVD that causes a CRC. (I think it works for computer files, etc. but I’ve never needed to try this.) Another trick is to copy all the files with Windows Explorer/My Computer, and only run CDCheck on the file(s) that produces the CRC. Then, from the folder that the repaired and copied files are in…burn that like it was a CD/DVD…this is just faster, CDCheck will do it all for you, it just takes a little longer on files that don’t need repairing. Using AnyDVD, in the background, allows one to do this to any copy protected CD/DVD, as well. It works GREAT!!! Good luck and enjoy repairing your messed up CD/DVDs. 🙂

  4. i have just finished backing up over 200gb of my files onto dvds only to find that i have been burning CRC errors into many of the discs, is there any QUICK way to test files readability so i can create a list of whats bad and whats not then get the bad files reburnt now the problem is fixed. ive tried CDCheck & IsoBuster they take forever to read the bad files. i need something that can just knock up a disc review quickly is there such a thing?? or maybe a way of reducing the amount of time windows spends tring to reread the bad info? so i can test the discs myself or am i better off starting from scratch?

  5. Dear Leo,
    I have tried everything recomended on this site about CRC. But nothing works. My friend said that he would let me borrow a DVD for a week with some files and pictures of his trip to places around the world, and I was so excited because he gave me permission the make a copy so I can keep a copy. But when I tried to copy it, “Error, Cyclic Redundancy Check” pops up everytime. There isn’t an scratches on the disk, nothing’s wrong with my computer DVD drive reader. I even tried to copy the file on my other desktop and my second laptop, but nothing. Please help:(

    Hash: SHA1

    Some combination of the problems listed in the article may simply make it
    impossible for you to read that DVD. Have your friend make sure he can still
    read it, and if possible, burn you another copy.


    Version: GnuPG v1.4.7 (MingW32)


  7. Hi all,

    SOLUTION: I also had problems with the CRC error when burning games. My try has been with two .rar games. What I did what was just to descompress the total file.rar into my PC and to install the games directly from the given data,through the setup.exe , without burning the game.
    When I was installing the game from the DVD I was getting the error but the same file descompress and installed without burning had succesful results. I hope it can help, though I know my comment is not very professional

  8. Leo, I need your help. I had copied some video files that I had purchased off a website and burned them to a c.d. Now, the c.d. worked fine but about a year later, I’m getting the cyclic redundancy message. I think my first mistake was using memorex c.d.s as I’ve used the Sony brand and they haven’t been giving me any trouble so far.

    I’ve tried everything: copying files to my desktop, to a folder, burning to DVD (I’ve lost three so far because of the error message) and I’ve even tried windows media maker on my desktop and laptop to try and save the video files. This isn’t the first time this has happened to me and I’m trying to avoid erasing the disc altogether as I spent a lot of money obtaining these video files. Is there any way to save what I have without erasing everything?

  9. I am getting a CRC error on a DVD with .NEF (Nikon RAW) photo files. For at least some of the troubled photos the thumbnail shows up, and Adobe can open a larger version as well so there must be enough data for that at least. Only it won’t let me COPY what I DO have. Some of them don’t display thumbnails; I assume these are lost causes – there may have been some dust exposure to the burner that wrote the DVD which could have corrupted the totally lost files.

  10. Try JFileRecovery (free on the net), it wouldn’t correct the problem but you’ll be able to still copy the files, even bad. In some bad files of jpeg format, you can still see the image and even correct it manually (photoshop or something) if you want it badly. This is better than nothing in case you can’t get the original drive that copied the file. Good luck.

    ps: i did get this error from my dvdcam recorder, and i understand the ‘centering’ issue about the disck been writen, and then trying to reread on a computer drive…:S

  11. JFileRecovery pretty much does for data files what EAC does for scratched Music CDs. No messing.
    I just recovered an old PST file from CD, that had 8 bad 512kb sectors on the end. Took about 5 minutes.
    Why MS don’t have this built into Windows is beyond me.

  12. THANK YOU LEO! I used condensed air to clean my CD drive AND my disk and … boom … my files came back! I have a Toshiba Satellite with a very sensitive Matshusita CD/RW drive. I can’t thank you enough. Another tip is to download ParetolLogic’s data recovery tool (its free) and try to find the copied files on your hard drive. It’s amazing what remains on your hard drive even after you think you’ve copied and deleted stuff. Even if you don’t need to recover files, its worth running just to see what is “out there!” Amazing.

  13. Hi LEO,
    m having problems installing games from rar files,while unraring them it always shows CRC error(CRC mismatch….)….it even shows error on games which i have installed succesfully earlier,but they too are giving the same eroor now,i have formated my pc too,still it ain’t working.
    What should i do???plz help me LEO.

  14. Regret, my Brand New SONY DVD Writer which was writting the CDs and DVDs perfectlly for around 2 monts now suddenly started to give trouble while writting the date on any media.

    It writes complete data on the CD/DVD but while at the final stage of writing the TOC it gets crashed (error log message is appended below.

    Some time, instead of writing teh data to the Media even without writting 1% of data it suddenly starts to write TOC by finalising the CD/DVD so wastage of Mrdia.

    Any suggestion please.

    Best Regards,

    Burning Error Log :

    Windows XP 5.1
    WinAspi: –

    NT-SPTI used
    Nero Version:
    Internal Version: 9, 0, 9, 100

    Recorder: Version: 1.70 – HA 1 TA 0 –
    Adapter driver: HA 1
    Drive buffer : 2048kB
    Bus Type : default
    CD-ROM: Version: 1.70 – HA 1 TA 0 –
    Adapter driver: HA 1

    === Scsi-Device-Map ===
    CdRomPeripheral : SONY DVD RW AW-Q170A atapi Port 0 ID 0 DMA: On
    DiskPeripheral : ST380211AS atapi Port 1 ID 0 DMA: On

    === CDRom-Device-Map ===
    SONY DVD RW AW-Q170A F: CdRom0

    AutoRun : 1
    Excluded drive IDs:
    WriteBufferSize: 83886080 (0) Byte
    BUFE : 0
    Physical memory : 1013MB (1037824kB)
    Free physical memory: 509MB (521332kB)
    Memory in use : 49 %
    Uncached PFiles: 0x0
    Use Inquiry : 1
    Global Bus Type: default (0)
    Check supported media : Disabled (0)

    CD-ROM (ISO)
    2:29:04 PM #1 Text 0 File SCSIPTICommands.cpp, Line 450
    LockMCN – completed sucessfully for IOCTL_STORAGE_MCN_CONTROL

    2:29:05 PM #2 Text 0 File Isodoc.cpp, Line 6789
    Iso document burn settings
    Determine maximum speed : FALSE
    Simulate : FALSE
    Write : TRUE
    Finalize CD : FALSE
    Multisession : TRUE
    Multisession type: : Start multisession
    Burning mode : TAO
    Mode : 1
    ISO Level : 1 (Max. of 11 = 8 + 3 char)
    Character set : ISO 9660
    Joliet : TRUE
    Allow pathdepth more than 8 directories : TRUE
    Allow more than 255 characters in path : TRUE
    Write ISO9660 ;1 file extensions : TRUE

    2:29:05 PM #3 Text 0 File Burncd.cpp, Line 3233
    Super Link activated

    2:29:05 PM #4 ISO9660GEN -11 File Geniso.cpp, Line 3349
    First writeable address = 0 (0x00000000)

    2:29:05 PM #5 Text 0 File ThreadedTransferInterface.cpp, Line 1029
    Removed 2 run-out blocks from end of track 0. Length: 355986 -> 355984.

    2:29:05 PM #6 Text 0 File Burncd.cpp, Line 3563
    Turn on Track-At-Once, using CD-R/RW media

    2:29:05 PM #7 Text 0 File ThreadedTransferInterface.cpp, Line 1029
    Removed 2 run-out blocks from end of track 1. Length: 355986 -> 355984.

    2:29:05 PM #8 Text 0 File FilesystemSettingsValidator.cpp, Line 142
    FS Settings: using validator ‘CUDFSettingsValidatorCD’
    ParamMode = ‘automatic’, changing UDF partition type from ‘physical’ to ‘physical’
    Changing UDF revision from ‘1.02’ to ‘1.02’

    2:29:05 PM #9 Text 0 File ThreadedTransferInterface.cpp, Line 1029
    Removed 2 run-out blocks from end of track 1. Length: 355986 -> 355984.

    2:29:05 PM #10 Text 0 File DlgWaitCD.cpp, Line 312
    Last possible write address on media: 359848 ( 79:59.73)
    Last address to be written: 355985 ( 79:08.35)

    2:29:05 PM #11 Text 0 File DlgWaitCD.cpp, Line 324
    Write in overburning mode: NO (enabled: CD)

    2:29:05 PM #12 Text 0 File DlgWaitCD.cpp, Line 2951
    Recorder: SONY DVD RW AW-Q170A;
    CDR code: 00 97 17 06; OSJ entry from: Moser Baer India Limited
    ATIP Data:
    Special Info [hex] 1: D0 00 A0, 2: 61 11 06 (LI 97:17.06), 3: 4F 3B 4A (LO 79:59.74)
    Additional Info [hex] 1: 00 00 80 (invalid), 2: 00 00 00 (invalid), 3: 00 00 00 (invalid)

    2:29:05 PM #13 Text 0 File DlgWaitCD.cpp, Line 499
    >>> Protocol of DlgWaitCD activities:

    2:29:05 PM #14 Text 0 File ThreadedTransferInterface.cpp, Line 756
    Setup items (after recorder preparation)
    0: TRM_DATA_MODE1 ()
    2 indices, index0 (150) not provided
    original disc pos #0 + 355986 (355986) = #355986/79:6.36
    relocatable, disc pos for caching/writing not required/ required
    -> TRM_DATA_MODE1, 2048, config 0, wanted index0 0 blocks, length 355984 blocks [F: SONY DVD RW AW-Q170A]

    2:29:06 PM #15 Text 0 File ThreadedTransferInterface.cpp, Line 958
    Prepare [F: SONY DVD RW AW-Q170A] for write in TAO
    DAO infos:
    MCN: “”
    TOCType: 0x00; Session Closed, disc not fixated
    Tracks 1 to 1: Idx 0 Idx 1 Next Trk
    1: TRM_DATA_MODE1, 2048/0x00, FilePos 0 307200 729366528, ISRC “”
    DAO layout:
    -150 | lead-in | 0 | 0x41 | 0 | 0 | 0x00
    -150 | 1 | 0 | 0x41 | 0 | 0 | 0x00
    0 | 1 | 1 | 0x41 | 355986 | 0 | 0x00
    355986 | lead-out | 1 | 0x41 | 0 | 0 | 0x00

    2:29:06 PM #16 Text 0 File ThreadedTransferInterface.cpp, Line 1029
    Removed 2 run-out blocks from end of track 1. Length: 355986 -> 355984.

    2:29:06 PM #17 Text 0 File SCSIPTICommands.cpp, Line 240
    SPTILockVolume – completed successfully for FSCTL_LOCK_VOLUME

    2:29:06 PM #18 Text 0 File Burncd.cpp, Line 4362
    Caching options: cache CDRom or Network-Yes, small files-No (

    2:29:06 PM #19 Phase 24 File dlgbrnst.cpp, Line 1767
    Caching of files started

    2:29:06 PM #20 Text 0 File Burncd.cpp, Line 4484
    Cache writing successful.

    2:29:06 PM #21 Phase 25 File dlgbrnst.cpp, Line 1767
    Caching of files completed

    2:29:06 PM #22 Phase 36 File dlgbrnst.cpp, Line 1767
    Burn process started at 32x (4,800 KB/s)

    2:29:06 PM #23 Text 0 File ThreadedTransferInterface.cpp, Line 2675
    Verifying disc position of item 0 (relocatable, disc pos, no patch infos, orig at #0): write at #0

    2:29:06 PM #24 Text 0 File MMC.cpp, Line 22511
    Set BUFE: Super Link -> ON

    2:29:06 PM #25 Text 0 File ThreadedTransfer.cpp, Line 273
    Pipe memory size 83836800

    2:29:31 PM #26 SPTI -1135 File SCSIPassThrough.cpp, Line 215
    CdRom0: SCSIStatus(x02) WinError(0) NeroError(-1135)
    CDB Data: 0x2A 00 00 00 02 80 00 00 20 00 00 00
    Sense Key: 0x03 (KEY_MEDIUM_ERROR)
    Sense Code: 0x0C
    Sense Qual: 0x00
    Sense Area: 0xF0 00 03 00 00 00 B7 0A 00 00 00 00 0C
    Buffer x072f0540: Len x10000
    0xEC 51 88 93 2D B6 DB 76 B6 5B 72 6C 28 CA 46 12
    0x3C 21 92 FD 90 CA 36 EF 3D B2 DA F1 98 D8 80 C0
    0xDA A2 88 64 38 74 29 36 A6 45 C0 57 B9 C5 56 27

    2:29:31 PM #27 CDR -1135 File Writer.cpp, Line 306
    Write error

    2:29:31 PM #28 CDR -201 File WriterStatus.cpp, Line 325
    Invalid write state

    2:29:31 PM #29 TRANSFER -18 File WriterStatus.cpp, Line 325
    Could not perform EndTrack

    2:29:31 PM #30 Text 0 File MMC.cpp, Line 17309
    start Close Track #2

    2:29:31 PM #31 SPTI -1176 File SCSIPassThrough.cpp, Line 215
    CdRom0: SCSIStatus(x02) WinError(0) NeroError(-1176)
    CDB Data: 0x5B 01 02 00 00 00 00 00 00 00 00 00
    Sense Key: 0x05 (KEY_ILLEGAL_REQUEST)
    Sense Code: 0x72
    Sense Qual: 0x04
    Sense Area: 0x70 00 05 00 00 00 00 0A 00 00 00 00 72 04

    2:29:31 PM #32 CDR -1176 File WriterStatus.cpp, Line 375
    Session fixation error

    2:29:31 PM #33 TRANSFER -19 File WriterStatus.cpp, Line 375
    Could not perform Fixation

    2:29:31 PM #34 Text 0 File WriterStatus.cpp, Line 384
    falling back to disc fixation

    2:29:31 PM #35 Text 0 File DVDPlusDualLayer.cpp, Line 1424
    SetDriveCaps: Set LAST LBA of layer 1 to 0

    2:29:31 PM #36 Phase 38 File dlgbrnst.cpp, Line 1767
    Burn process failed at 32x (4,800 KB/s)

    2:29:31 PM #37 Text 0 File SCSIPTICommands.cpp, Line 287
    SPTIDismountVolume – completed successfully for FSCTL_DISMOUNT_VOLUME

    2:29:31 PM #38 Text 0 File Cdrdrv.cpp, Line 11444
    DriveLocker: UnLockVolume completed

    2:29:31 PM #39 Text 0 File SCSIPTICommands.cpp, Line 450
    UnLockMCN – completed sucessfully for IOCTL_STORAGE_MCN_CONTROL

    Existing drivers:

    Registry Keys:
    HKLM\Software\Microsoft\Windows NT\CurrentVersion\WinLogon\AllocateCDROMs : 1 (Security Option)

  15. Trying to install game

    it gets quarter way through and comes up with this
    Feature: Game Files
    Component: Files
    File: D:/Setup/
    Error: Data error (cyclic redundancy check)

  16. I keep getting this notice (Data error (cyclic redundancy check) 0x80070017) every time I try to backup my computer onto a hard disc drive. Does that show a problem with the hard disc drive or with the files on my computer?

    Could be either. You’ll need to do something else that tests one at a time to figure out which. (Or, if the error message said more than just that, perhaps there’s a clue in there.)


  17. My DVD Drive is slow, last week was fine and fast. Some guy told me to set up PIO or DMA thing and then I tried to rebot my PC and insert my mag disc. I get Copy fail (cyclic redundancy check) and I tried again was OK. It just randomly sending out this error, help pleaseeee….

  18. I am getting rid of CRC error!!
    Recently,i bought a DVD movie and when i try to copy files from this DVD,i got CRC error.When i went back to the shop to change it,it runs fine on their computer!!!! 🙁
    I think that there is some fault in my DVD ROM.Please give me solution.Thanks.

  19. Hi.
    I’m experiencing the CRC issue quite often now but not with CDs/DVDs but when downloading media or extracting files from archives (I’m using winrar); even when copying my files from one PC to another or one drive to another.
    I tried re-installing my windows but I couldn’t fix it.
    Do you think it may be the HDD or the RAM?

    The hard disk, almost certainly. It has a bad sector on it. How do I fix a bad sector on my hard drive?


  20. I know that this topic is old, BUT…

    what I (and apparantly, everyone else) am looking for is a “1” that can be changed to a “0” somewhere in HKEY_LOCALMACHINE

    A CRC error is a physical defect or hardware inabiliry to read. There’s no registry setting that’ll change that.


  21. i burn a 3 parts of call of duty modern warfare 2 and the 2nd dick was went wrong. It Says “DATA ERROR Couldn’t read the disk”

  22. I have an external hard-drive on which are stored lots of family photos. When I put it into the laptop and tried to access it, I was told that the external hard-drive needed formatting. I declined and plugged it into my partner’s laptop which came up with the CRC error message. I’m terrified of losing all of my family pictures. Do you have any advice? Many thanks, Ben

    This article: How do I fix a bad sector on my hard drive? – and the realization that you should start backing up files you think are important. If they’re in only one place, they’re not backed up.


  23. If you attatch a label to a CD or DVD it can cause a cyclic redundancy error if the label is not perfectly smooth .If this occurs remove the label and use a professionally produced label

  24. Help required I can not access my portable HD, as it says Cyclic Redundancy Check, and wants to format my portable HD. This was caused by not closing a document before removing portable HD, I need to access these files any help please would be appreciated

  25. I’ve noticed a connection between bad fragmentation and the CRC. I always get more errors when my hard drive is heavily fragmented, or if the computer needs to be restarted. It also helps to remove extra peripherals (such as 3 extra hard drives, etc).


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