How To's

Canon’s Error 99: the Man, the Myth

Published December 31, 2008

This article was updated in April of 2009 after Mark at Precision Camera, our favorite repair shop, provided us with some additional information.

This is probably the most boring article I’ve written for LensRentals. (Personally, I like Smashed Front Element the best.) But, I love a good mystery, and I love debunking dSLR “urban legends”. Every so often I run across an online forum where someone makes broad statements about Error 99 which I know are incorrect or at least incomplete. As is my practice, I’ve boldly charged into these online gunfights devoid of intellectual ammunition (i.e. facts). And predictably, the intellectual level of the discussions quickly spirals down from “Is not”, “Is so” into the traditional online-forum sign-offs of “You get Err99 because you’re a bad photographer” and “if you’ve never gotten Err99 you’re obviously not taking many pictures”.

Because Canon Corporate apparently believes that releasing no information about a problem makes it go away, there is little factual information to debunk the online myths regarding Err99 unless you really do a lot of digging. Googling Err99, Canon EOS error codes, etc. brings up several dozen pages of links most of which are the above mentioned “discussions”. There are a few nuggets of truth out there, though. The most complete of these is a multi-year 2,300 post discussion of Err99 problems at Richard’s Notes. There are also a few thoughtful and factual discussions that have taken place in some of the better forums online. After spending far more hours than I intended looking through these sources to settle an online debate, I thought I’d write a summary of what I found and what we’ve experienced here— LensRentals has over 700 Canon lenses and over 50 Canon bodies (as of December 2008), so we have a bit of Err99 experience.

The Myths

Some of the most common Err99 myths are listed below. Strictly speaking, they are not myths; almost every one is true. The myth part comes from thinking that any one of them is actually the cause of Err99. So:

  • Err99 results from an electronic communication problem between the lens and the camera.
  • Err99 results from using third-party (i.e. Sigma, Tamron, Tokina) lenses.
  • Err99 means that electronic circuitry in the lens has failed.
  • Err99 means that electronic circuitry in the camera has failed.
  • Err99 results from using third party batteries.
  • Err99 is a firmware issue, and can be fixed by upgrading to the latest firmware.
  • Err99 started with Canon XT and 20D cameras.

There are a lot more. Almost all of them are true for at least some cases of Err99. The best myth, though, is that Canon purposely created error 99 to prevent the use of third party lenses. As best I can tell, that one isn’t really true, but it does make fun speculation. And, of course, Canon’s nearly total silence on error 99 and other problems certainly helps feed the conspiracy theorists among us.

Author: Roger Cicala

I’m Roger and I am the founder of Hailed as one of the optic nerds here, I enjoy shooting collimated light through 30X microscope objectives in my spare time. When I do take real pictures I like using something different: a Medium format, or Pentax K1, or a Sony RX1R.

Posted in How To's
  • Andy

    I got yesterday my first ERR99 and today I found out it is the shutter. I have a 40D with 17-85mm lens. Today I swiched to live view without the lens and the shutter remains closed. I tried to open it with Manual Cleaning function, it opens then closes and I get the error. Seems I need a new shutter 😐

  • D Cherrill

    I have a 20D that I use, or try to use, with a Sigma 28-80 APO zoom, and I am plagued with error99. I have found that the lens will not stop down when using the DoF preview button.
    I have re-set the camera more times than I care to remember, it works fine without the lens, which is a pitty as its a lovely camera and the Sigma is a nice lens to use (on my EOS5 film SLR it stops down O.K) so I must assume it is this thats causing the problem.
    As soon as I can I am trying a Canon lens on the body to see if that makes any difference.

  • O8h7w

    sounds like you have already pinned it down to the aperture mechanism of the lens, don’t you think so too?

    I wouldn’t doubt it except if I had seen the error while keeping the aperture at f/2.8, where it doesn’t have to move. However, if that happens, I can’t think of any explanation except an additional problem. Oh, this means I wouldn’t doubt in that case either…

    Anyway, I don’t know what you can do about it other than keep to shooting at f/2.8 or buy a new lens. My guess is that repairs are feasible (hence available) only for really expensive lenses. If it were my lens, I would take it apart! 🙂

    Happy shooting /O8h7w

  • Naveen Chhillar

    I own a Canon 400D with 3-4 different lenses from Canon, Tamron, Tokina. However, when I mount my Tokina 11-16mm F/2.8 – it shows this Error 99. Particularly, when I try to lower the aperture below 3.2. Also tried this lens with another Canon Body (1100D) but same error there as well. Tried to clean the lens contact points using eraser, as suggested in some other forums. But, without success.

    Can anyone suggest something here ??

  • O8h7w


    if I were to guess, the newer and bigger lens draws a lot more power and your battery is beginning to show it’s age. Try borrowing a fresh battery, if you can.

    Wishing you luck /O8h7w

  • George

    I tested a brand new lens Zoom Quantaray 70 -300 mm about 50 shots
    and it error’d 99 at least 3 x per 10 shots.
    I switched to the older standard Canon 18-55mm that came with my Canon Rebel EOS 300D and took 40 shots at my garage – same pic , manual settings on both – never had an error 99.
    If I were to guess that there is something that Canon did to these early models to keep users from buying the “cheaper ” brands, the succeeded.

  • Richard

    I have an EOS20d (about 10 years old) with the standard Canon EFS 17-85 set up. I also have a Sigma EX wide angle (about 4 years old).

    The Err99 comes up with the standard lens bit NOT with the Sigma. That leads me to believe that the lens electronics on the Canon may be faulty.

    To be frank – the image quality off the Sigma is superior to the Canon (it seems I’m not alone in thinking this). It makes sense – Sigma live or die by the quality of their glass – Canon make umpteen other products.

    I’m in the throes of upgrading the equipment for my business. Now – I’m seeing problems with Canon lenses and hearing about some of the ‘indifference’ of Canon towards customers – I’m starting to get concerned.

    It seems a far cry from the great days of brass-chassied high quality 35mm and medium format bodies and corresponding high quality lenses that didn’t contain all this electronic frippery in everything. I’ll cherish the memories of those days and feel a bit sorry for those who’ll never experience the joy of a superbly engineered manual camera and proper ‘hands on’ photography.

    These days – they are all as soulless (and problematic) as owning a PC!

  • O8h7w

    It seems like your Sigma lens has trouble stopping the aperture down. First try to find which apertures work and which don’t (using manual exposure settings). Then grab any chance you can find to try the lens with another EOS camera (at an aperture that gives the error on your camera). This way you should be able to confirm that the problem is with the aperture of the lens.

    Good luck 🙂

  • Joe

    I have always had problems with my Sigma wide angle lens and no other when I use it with my good old Rebel XT. I had no such problems with the Sigma lens and my Canon S10. What’s even more puzzling is I can get the Sigma lens to work indoors in low light, but as soon as I step outside or into a bright room, it gives me the old Err 99. Cleaned the contacts… no difference.

  • O8h7w

    I’m guessing you have tried letting the camera sit without power for quite a while – I would recommend a day or so to let any and all moisture out of the camera – and then tried it with optimum conditions, that is, no lens no card and a freshly charged battery.

    If the shutter is not opening when you try to take a shot, activate live view or activate manual sensor cleaning then obviously something closely related is wrong.

    It would seem that most probably the shutter itself is at fault, but as far as I can see it could also be an electric fault earlier in the chain so that the shutter does not get the signal to open. I’m pretty certain the camera itself knows which is the case, this is the frustrating part.

    The shutter on my own 40D does not open. It throws error 99 at me at the end of a shot and after flipping the mirror up and immediately back down again when I try to activate manual sensor cleaning, but not when I activate live view. The mirror goes up but the shutter does not, and the screen just looks like I forgot to take the lens cover off. I can’t see anything wrong with the shutter, so I’m taking mine apart when I have the time – in June, hopefully.

    My question to you is therefore only out of curiosity; does your 40D throw error 99 or not when you try activate live view?

    Cheers /O8h7w

  • Akm

    My canon 40D was working very well with all my lense like Canon 28-135mm and Tamron 28-300mm. But most of the time i was using canon 28-135mm lens. On that day I just took 5/6 photos and than suddenly the camera showd err 99 and stopped working. I did everything like lens contact clean, charge the battery, change the CF card etc etc. But same problem. Even without lens it does not work. Live view also does not work. So I look closer inside the camera and I can see the shutter leaf is not opening. It always remain close. So can i now be sure that it is the problem of shutter ? Any idea ? Anyone got this type of problem ?
    i am not a professional photographer so i did not use this one all time. Shutter count should be 6,000 to 7,000. By the way thanks for great article.

  • O8h7w

    Good to hear your camera is fully working again, and for a reasonable price at that!

    I asked for a shutter replacement in a local shop, the wrong one it seems. The answer was that they could send it to Canon for the not-so-reasonable sum of 3800 SEK = 560 USD… sometimes, Sweden is not the best place to live. Then again, when the camera works, it’s a great place 🙂

  • Bharat

    Took the 20D to a local (non-Canon) repair shop in San Jose, CA. Some contacts had to be re-soldered, which fixed the problem ($165). Also got the shutter replaced as it had already had over 90K actuations for additional $60. Now the camera works like new.

  • O8h7w

    Disclaimer: This is all just as far as I can tell, could be wrong. While I do have some general experience with electronics, I don’t really have any experience with this problem – I have only read a lot.

    It sounds like your camera does “work” as supposed without a lens. When the problem arises with different lenses but not without a lens, I’m pretty sure the problem has to be in the connection between lens and camera. However, this need not mean the contacts you can easily reach – it could be corrosion somewhere on the same signal path further within the body.

    But the pattern you mention suggests there is something more to it. I would test more, with more lenses and cameras and batteries and so on – all I could possibly variate. Then I would sit and think about it for a while.

    If that doesn’t find the problem, I would say it’s time to take things apart!

    Good luck 🙂 / O8h7w

  • Bharat

    My Canon 20D started to throw Err99 a couple of days ago. Tried various suggestions mentioned here (different battery, cleaning lens contacts on body as well as the Canon 50mm 1.8 lens). The only pattern that I have found is that if I remove the lens, then press the shutter release button a few times, and then replace the lens, then I am able to take a few shots (varies from 5 – 20). After that, the Err99 appears again. Wonder if anyone has encountered similar scenario and if you were able to resolve the issue?

  • O8h7w

    I have a 40D with Err99 behaving rather peculiar. Tried everything in this list, closing in on the shutter as a likely cause. The weird part is what happens when I try manual sensor cleaning and live view.

    Manual sensor cleaning causes the mirror to flip up and then back down immediately, with an Err99 message. I haven’t seen this behavior mentioned anywhere yet.

    Activating live view causes the mirror to flip up, but the shutter does not open. And no error message – this feels strange. Trying to take a shot from here, it gets even weirder. After a pause equal to the shutter time, the shutter now seems to (or at least try to) move, then the mirror comes down and I get the Err99 message.

    I read somewhere (maybe in this article?) that the Err99 message is hard linked to only one thing: the self-test that is done when you take a shot. That would explain that there is no error message when activating live view – if only that statement wasn’t already looking like it’s false, since the manual sensor cleaning causes the message to appear.

    It seems to me pretty clear that the shutter has broken down, but I don’t see anything wrong with it and I wouldn’t want to change it if the problem actually is in the electronics department. And odd behavior usually means faulty electronics, in my experience. So, could anyone enlighten me as to whether this is odd behavior or not?

    Lastly, many thanks to Roger Cicala as well as the internet as a whole for making this information available! 🙂

    Sincerely, O8h7w

  • dncingrl

    I have a two year old Rebel xs that has started with this err99. We only have two canon lenses so I am not hopeful that it is an easy lens fix. I do recall the camera taking a slight bump while hiking one day and I am pretty sure the error started just after that. I am in the process of trying some of the fixes listed on another site and I am hoping that something works!!! If anyone has any other suggestions, please let me know.

  • It is an aperature related problem. Thank You for your help. above 5.6 or so the it gives me the error code 70 percent of the time.

  • I have tried the aperature at anywhere from 3.5 to 32 since it started last week and havent found any patterns. I cleaned it with an eraser and it has gotten a lot better but it still randomly pops up from time to time. I took it to the camera store and of course it worked perfectly there. I switched lens and out of the 20 or so shots I took it didn’t show up at all. Tomorow I will be shooting a lot with both lenses so I may find something.

  • Roger Cicala

    I have no idea how common the problem is, but if your Tamron is working well I would bet the problem is with the lens. Changing aperture size may show you if the problem is with the aperture system (fairly common).

  • Wow thank you so much for the article I actually was dissapointed when it ended at page six. I recently bought a Canon Rebel XT second hand and for the first 7 thousand pictures it was fine but recently it has popped up all the time always right when I am about to get the perfect shot. I have narrowed the problem down to my 18-55m IS-F lens as the camera is fine with my 80-210 Tamron. I cleaned the connections and it seems to be really hit or miss. It seems like after I turn it on it will either show the dreaded code right away or not at all until I change the settings. I havent found any rhyme or reason to it yet but I will keep on looking. My question is if I should buy a new lens or a new body. I am paranoid that if I buy a new lense the problem will develop on the other lenses or if I buy a new body the lense will still not work. I knew I should have gone with nikon! lol this week i will go to the camera shop and test the body with differant lenses and the lense with differant bodies. Do you have an idea of what the percentage of cameras have the problem?
    Thanks a million.

  • Peter B

    I get err99 when the 18-55mm lens is in wide or nearly wide. Zoomed in the problem does not occur. i am currently trying the last fix suggestion from this page. I suspect that it will not work. I agree with some of the comments – Canon are ignoring a common problem..

  • Again in brief, the things that may be done are:
    Check: CF card (format), lens (e.g. with no lens), camera lens contacts (clean with rubber), check batteries including button battery, upgrade firmware, de-moisturise, blow clean, realign shutter blades if squew (with risk), try live mode (if it works tells you it is a mirror problem perhaps).

    Mine works in live mode. I can’t feel/see/hear anything wrong with the mirror.

    Second hand 40Ds are now about the same price as the repair, for about 100 USD more I can get one with a handy lens, shutter replaced. I would have a spare grip, charger and three extra batteries. This cover all tell nothing, high-cost-to-repair error upsets me and makes me think that I’d rather pay someone other than Canon.

  • Peter

    I get error 99 on my Eos20d and the shutter continually activates on turning on the camera. I contacted canon and got the same try this and that email. Not getting an answer from them or a fix I will not trust their products again. Any company who ignores its customers and sells a product that suffers a common fault should be held accountable or boycotted. I would suggest this company is not trading fairly and with the amount of dissatisfied customers kept in the dark about the fault, a petition could be compiled and sent to the office of fair trading standards.

  • Andrew

    I just ran into this problem on my 450D while connected by USB using Digikam, trying to download a wad of raw images. It kept occurring, breaking the USB connection, even though I wasn’t taking pictures. Eventually, I determined that it was related to machine load, as I was also tone mapping some HDR images at the same time. I waited for the tone mapping to complete, then re-initiated the download. I successfully downloaded 2.6GB of images, twice, with one connection while the computer was lightly loaded. As a software engineer, my guess is that the Canon USB firmware has some dodgy empirical time-outs built into their code, which are triggered when the USB connection data moves in fits and starts. Either the Canon USB code or the camera throws in the towel, and the non-specific Error 99 is put up (after a number of seconds). Which explains why USB connections with the camera can be hit-or-miss, generally taking several tries before succeeding.

    This leads me to believe that “Error 99” is either a “catch all” error code, dumbed down for the user (as an insult from Canon), or similarly, a general “Communication Failure” error for any subsystem in the camera. Either way, aftermarket lenses that have had to reverse engineer the EOS EF protocol may miss some corner cases, leading to a communication failure. The same problem can occur under a “brown out” (low voltage) condition due to resistive (dirty or worn) contacts or bad battery cells. Logic circuits may or may not operate correctly at low voltage conditions – they are only spec’ed to work above a minimum voltage. Below that spec, you span the gamut of correct to non-operation, including incorrect operation, varying with temperature. Which would lead to communication problems between the camera CPU and the subsystem.

    It is unfortunate that Canon has not bothered to answer customer concerns by updating their firmware to display more informative error messages, nor explain the causes of the message. Speaking for myself, I would blame this on poor firmware coding, a lack of coding standards, and a detached management who is more about product marketing than customer support. Too many marketing types are too “busy” to actually learn about the products, and think firmware/software is “magic” and are not interested in hearing about it. Which leads to a lack of emphasis on the firmware, which is dragged and patched from product to product, without the resources to ensure a quality, stable build for each product.

  • AJ

    I have a Canon 450D – I have had it for about 3yrs without fault, until yesterday!! This fault occurred when on live view while taking photo’s of the lunar eclipse – buggered if I know what I did!!

    Error 99 appeared out of the blue.. Now when trying to take photo’s noticeably when flash is required it initially displays BUSY then the error 99..

    Trying to resolve matter I have checked out various forums – I have recharged the battery, cleaned lens & camera contacts with soft cloth, tried swapping lens – but still the fault appears!!

    This article is brilliant – don’t yet know if any of the suggestions will work – but thank you for providing this information..

    I am keen to know if others have suffered similar error using Canon 450D.. Did you fix the problem?? What turned out to be the fault??


  • This is the best article on this issue. Fortunately it is linked from the mega thread at Richard’s Notes. I have Err 99 on my 40D. I sent it off for repair and was told 340 USD. I declined and had the camera sent back. It came back with no information regarding the source of the fault or even a repair quote. I was thinking to try the self-doable fixes: lens changing, card changing, battery replacement (button or main), contact cleaning, and shutter blade realignment but if the repair people have more information then I guess that only the last is an outside hope, since the repairers would have tried the others. I note that on Japanese ebay an err99 camera is getting quite a lot of bids suggesting that some folks are hoping for a self fix.I wish Cannon would give us all the more detailed information (maybe using the words “may be”). It also seems to me that this error has a built in obsolency feel too it. So the camera has found an error that it can not diagnose. I wish it would just go ahead and record the photo displaying an error message, even if the quality is degraded. The camera seems to be deciding “if it is not perfect, then don’t take the photo at all.” Please give us the info and the options Cannon.

  • Roger Cicala


    A voltmeter should do it, and be sure to check with the battery partly discharged. Some bad cells can maintain voltage at full charge but not at half charge.

  • Roger.. great stuff! I have a eos 400d and just got a 2nd hand tamron lens which was in full working order when sold…
    when i put it on my body i get intermittant err99 messages, sometimes at certain angles, sometimes once, twice, three times in between resetting it and shooting a few pics. Any way i can check my batt voltage? will a multimeter do? Its a few years old. Cleaned contacts with eraiser…. im a bit stuck for ideas now?

  • Jeremy

    Ashish, did you ever get your camera fixed? I have a 40d with the same problem, it only works in Live View and cleaning the sensor manuelly causes the same error, so I’m guessing its a shutter problem.

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