How To's

Canon’s Error 99: the Man, the Myth

Published December 31, 2008

Experience at

There are a number of “what to do when Err99 occurs” lists that I’ve summarized below. Before we jump to them, though, I think its important to try to narrow down the Err99’s cause, rather than to go through the list and hope everything is better. I realize “finding the problem” sounds remarkably obvious, but bear with me for a second. With hundreds of lenses mounted to hundreds of different cameras at any one time, we deal with a lot of Err99 problems. Some Err99 issues are specific and immediate: suddenly the camera starts giving Err99 with almost every shot. Resetting the electronics helps for a few shots—or doesn’t—but the problem recurs and the camera is basically useless. These “catastrophic” Err99 episodes usually means there’s been a major injury in the camera or lens: shutter failure, circuitry burnout, etc. Sometimes the fix is easy—new battery, smoothing a jammed shutter curtain, changing lenses, etc… but most often a trip back to the mothership for either the camera or the lens is in order.

Other Err99 problems are more subtle: Err99 shows up after a lens change, lets say. Cleaning the contacts makes it go away, but it comes back a week later, getting more frequent over time. It may just be with one lens at first, but may start occurring with other lenses. In these cases I think it important to remember the point about electrical voltage made above: if voltage drops below 7.3V in the camera’s circuitry, Err99 is likely to occur. Voltage drops across different connectors are cumulative, and batteries produce less voltage as current increases. What may seem a case of dirty contacts may really be a narrow power margin, due to oil on the lens contacts, an old battery that’s not producing its rated voltage when fully charged, a lens that’s sucking down power to run the IS servos, which finally drops below the lower operating threshold when autofocus is activated. Cleaning the lens contacts might help, but that doesn’t make it “the problem”. So, be careful when diagnosing an intermittent problem. Its also important to do everything you can to narrow down the problem. Sending the camera to Canon for “intermittent Err99” without more information is likely to lead to “can’t reproduce problem” at the Canon Service Center.

For example, once or twice a month we’ll have a customer tell us “the lens is causing Err99 on my camera, none of my other lenses do that”, so we send them a replacement. We have the luxury most individuals don’t get in that situation: the ability to test that lens on multiple cameras, plus the customer will try another copy of the same lens on their camera. In some cases, the customer will tell us the second lens is the same as the first on their camera; meanwhile, the first lens seems fine when tested on other bodies. Here, the problem is a weakness in the customer’s camera body that became apparent only when a lens with heavier power requirements was used. In other cases, the second lens works fine for the customer and the first lens, when returned, gives Err99 on other bodies. Again, problem obvious, the lens had internal damage to the electronics or aperture system.

In a lot of cases though, the problem is less obvious. The new lens works fine for the customer, the old one seems to work well on other bodies. At first, we just shrugged our shoulders and said “one of those things” but over time, as we track the problems that occur with various copies of lenses and cameras, something became apparent to us. Unless we found the specific cause of Err99 and corrected it then the problem, while intermittent, would recur. We’ve worked on developing an Err99 stress test for lenses that only show the problem intermittently: we use an older camera body, halfway charged battery, and take up to several hundred shots being sure to change the aperture, zoom, and focal distance frequently. Doing this we’re sometimes able to reproduce the problem in a lens that otherwise seems to have just had some isolated Err99 reports.

That being said, there are also circumstances where Err99 has occurred and then never, ever happened again:

  • Using older battery (solved after replacing battery)
  • Bad CF card (solved after replacing card)
  • After marked temperature change (solved after letting the camera sit for a day or so, probably condensation)
  • After mounting battery grip (solved after remounting the battery grip)
  • With single lens only, all other lenses fine (solved by repairing the lens)
  • Early copies of 50D (solved after firmware update)
  • Camera used with third party shoe mounted flash (solved after flash removed)
  • Dirty contacts (solved by cleaning, sometimes that is the only problem)
  • For no apparent reason, it went away for good after doing the routine Err99 protocol. This part reminds me of “any sufficiently advanced technology is indistinguishable from magic”…

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
  • Butch Teel

    Thanks for nothing. I don’t see anything in your post which is positive except saying nobody knows what error code 99 is supposed to indicate. I have a stock Rebel XT. I have tried removing the lens and then putting it back on; I’ve checked the pins for the storage disc (which gave me an error of (0). I’ve tried to reformat but that gave me the error 99 which led me here.

  • Tango GF

    Thanks a lot for your help, everything seems to work, I’m new to the camera, it’s already used and I was very sad because I thought I had broken it, and your article served me a lot

  • cleaning the lens contact worked for me…ty

  • It sounds like a shutter replacement is going to be required, I’m afraid.

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