Hey Everyone!
Within two days – I lost two of my beloved cameras! 
First one – my old and trustworthy Canon 60D – 7 years old – 237,000 clicks – started showing black bars on photos and after a few photos – just died and "err 20" shows up no matter what I do. Looking inside the camera - I can see the broken shutter... It's dead.
Ok, that sounds reasonable – the shutter gave up after more than twice what Canon warrants (100,000)…
But – two days later, my barely ever used Canon 500D – 6 years old – only 6,000 clicks (!!!) – started showing black bars too and then also died with "err 20". Is this even possible? It's was very lightly used and never took a beating or anything like that...
What is even crazier is – I just got a brand new Canon 80D – and started using it with my Yongnuo 35mm f/2.0 - suddenly I got some over-exposed photos. I found out that the aperture blades are not closing all the way. They don’t close any smaller than f/3.2. So when taking pictures in f/2.0 – f/3.2 – everything works good. Whenever I set it to f/3.5 and "higher" (f/5.6… f/8…) the camera freezes with "err 01" – lens communication error.
Why am I telling you all this? A few questions I would love to know the answer to, and you might help –
- Is there any logical relation between the broken lens and the camera that might have caused the error and damaged the camera(s)? Or maybe the other way around? The faulty camera broke the lens?
- Should I continue using the 35mm lens (I will always use it wide-open, or f/3.2 tops)? Can it cause any damage to new cameras I'll be using?
Is this some crazy three-way coincidence or what?!
The definition for error 01 and 20:
- Err 01: Lens to body communication error
The camera to lens communication is somehow being interfered with… could be a problem within the lens itself, possibly the camera body, or something as simple as a smudged fingerprint on the lens mount contacts.
- Err 20: Mechanical malfunction
Within the mirror, shutter or aperture mechanism (most likely), some sort of disturbance, error or lock-up has been detected. This error code doesn’t specify where the exact problem is, but points to the cause being mechanical rather than an electronic gremlin.
Thanks for reading 
@golot7 wrote:
Hey Everyone!
Within two days – I lost two of my beloved cameras!
First one – my old and trustworthy Canon 60D – 7 years old – 237,000 clicks – started showing black bars on photos and after a few photos – just died and "err 20" shows up no matter what I do. Looking inside the camera - I can see the broken shutter... It's dead.
Ok, that sounds reasonable – the shutter gave up after more than twice what Canon warrants (100,000)…
But – two days later, my barely ever used Canon 500D – 6 years old – only 6,000 clicks (!!!) – started showing black bars too and then also died with "err 20". Is this even possible? It's was very lightly used and never took a beating or anything like that...
What is even crazier is – I just got a brand new Canon 80D – and started using it with my Yongnuo 35mm f/2.0 - suddenly I got some over-exposed photos. I found out that the aperture blades are not closing all the way. They don’t close any smaller than f/3.2. So when taking pictures in f/2.0 – f/3.2 – everything works good. Whenever I set it to f/3.5 and "higher" (f/5.6… f/8…) the camera freezes with "err 01" – lens communication error.
Why am I telling you all this? A few questions I would love to know the answer to, and you might help –
- Is there any logical relation between the broken lens and the camera that might have caused the error and damaged the camera(s)? Or maybe the other way around? The faulty camera broke the lens?
- Should I continue using the 35mm lens (I will always use it wide-open, or f/3.2 tops)? Can it cause any damage to new cameras I'll be using?
Is this some crazy three-way coincidence or what?!
The definition for error 01 and 20:
- Err 01: Lens to body communication error
The camera to lens communication is somehow being interfered with… could be a problem within the lens itself, possibly the camera body, or something as simple as a smudged fingerprint on the lens mount contacts.
- Err 20: Mechanical malfunction
Within the mirror, shutter or aperture mechanism (most likely), some sort of disturbance, error or lock-up has been detected. This error code doesn’t specify where the exact problem is, but points to the cause being mechanical rather than an electronic gremlin.
Thanks for reading
While it is unlikely the lens and shutter failures are related. The lens failure is typical of the issue old 3rd party film EOS lenses had with EOS digital cameras. Those lenses drew too much current when trying to close the aperture and it would not close down when taking a photo.
