dleebrick Loc: Indian Land, South Carolina

Was out in the field photographing waterfalls, switched lenses to my EFS-10-22 wide field lens, turned the camera on and ...ERR 20 "shooting is not possible due to an error". Turned off camera, tried again, same error. Switched back to my EFS 18-135 lens. No problem. Cleaned contacts on my EFS 10-22, tried again, same error. Switched back to 18-135, no problem.
When I got out to a spot where I had cell reception, I looked up ERR 20 and most solutions said to turn off camera, remove battery, remove lens, try again. Error apparently is some mechanical issue with the shutter that usually requires a service call. Did multiple times, didn't work. Put on 10-22 lens again. Still got ERR 20. Removed lens, happened to notice a small 1" o-ring sitting off-kilter over the camera mirror. Looked at the lens and something looked a little different. Turns out that the o-ring is part of the inner mating surface of the 10-22 lens and had come loose. Replaced the o-ring on the lens, put the lens on the camera, and no more ERR 20!
Haven't seen this listed as a possible solution to ERR 20 problems, so thought I would share it. Looked at my other EFS lenses and they don't seem to have a removable o-ring, so maybe that's unique to the wide angle item.

insman1132 Loc: Southwest Florida

Great work in the field. Well done.

leftj Loc: Texas

Thanks so much! I also have an 80D and the same 10-22mm lens although I have never experienced this error problem. I am copying this and putting in my reference documents.

CHG_CANON Loc: the Windy City

The bookmark feature of the site exists for this purpose ....

rydabyk Loc: Florida Panhandle

Thank You!

Tikva Loc: Waukesha, WI

How does the bookmark facility within UHH work? I've never figured it out.

jmvaugh Loc: Albuquerque

Great field work! I have the 80D and was considering a wide angle lens if Santa’s feeling generous this year. I book marked this for future reference. Thank you!

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

This isn't an 80D problem, since it involved an 'o' ring coming loose from the lens, it could happen on any camera - at least any Canon APS-C. I have an 80D, a T3i, and the EF-S 10-22 lens. I have never experienced that problem, but 'things' happen sometimes. It helps to know so that any owner of that lens should take a note and has a look. First thing that I did this morning, but I have no concerns, it may just have been a freak event unless the lens has been dropped or treated roughly or something.

I hope Santa is feeling generous. The EF-S 10-18 and 10-22 are both good lenses, the 10-22 is more expensive, but is about as close to an 'L' quality lens as you can get within the EF-S family.

CHG_CANON Loc: the Windy City

Tikva, ref bookmarks, have you ever tried to "remember" a post from the past? Well, you might have responded or otherwise added to your "watch" list and kept it there maybe a few or many pages into the past. Or, you might use the site's weak search function if you can remember what to search for. Or, maybe even you use google against the site with relevant words from the original text... However, if you bookmark the entry along with your own descriptive title, finding it on your bookmark list is the quickest.