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EF 50mm f/1.8 STM Lens Generates "No Lens Attached" Error on EOS 77D



  I am using a Canon 77D. Yesterday, I bought a Canon 50 mm f/1.8 STM. But when I try to change the aperture it is giving me the message "cannot adjust aperture, No lens attached."  I  have no idea why this is happening. I have a canon EFS 55-250 mm lens, with which I can change the aperture and everything works fine. Please help. Thank you.


From personal experience, the mount can be a tiny bit tight when that lens is new. Are you sure it's all the way locked into place? Check out this KnowledgeBase Article for instructions: 

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My 80D is my only camera with the lens retract feature. I also own the EF-S 24mm f/2.8 STM, EF 40mm f/2.8 STM, and EF 50mm f/1.8 STM. None of them cause an error if I remove the lens while the camera is on. 

Try using your 5D Mk IV with another STM lens, or try your EF 50mm f/1.8 STM on another camera with the lens retract feature. The error message should not happen just because you remove the lens with the power on. 

Can you show us a screenshot of the error message?


Mike Sowsun

I doesn't always happen. But it happens every once in awhile. But after updating the camera's firmware I haven't seen it. But when it does happen it's says "Lens communication error". 


Current Gear: EOS 5D Mark IV, EF Trinity, EF 50mm F/1.8 STM, EF 85mm F/1.8 USM, 470EX-AI & 600EX II-RT

Retired Gear: EOS 40D & Sigma 17-50mm F/2.8 EX DC OS HSM