Canon 6D Mark II Error 20: Shutter Replacement

If your Canon 6D Mark II shows Err 20 and locks up mid-shoot, the camera is reporting a mechanical fault — and in our experience it very often points to the shutter. An err 20 Canon shutter replacement is a routine repair for our lab: we fit a complete new shutter unit and recalibrate the camera at a fixed price of €250.

The symptoms

The camera displays "Err 20: Shooting is not possible due to an error. Turn the camera off and on again or re-install the battery." and stops responding. Typical behaviour includes:

• The error appears during burst shooting and the camera freezes.
• The only way to bring it back to life is removing and reinserting the battery.
• At first the error is occasional, then it becomes more and more frequent with every outing.

What causes it

On all Canon bodies, Err 20 is a generic message indicating a mechanical malfunction. It can be triggered by a number of different components, but it is frequently connected to the shutter mechanism.

In the camera from this case study, a full disassembly revealed an internal shutter gear that had broken off and was loose among the surrounding components. Worse, every time the camera powered up and tried to shoot, it kept driving current into the jammed mechanism — aggravating the damage with each attempt. That is why an Err 20 that starts as an occasional annoyance tends to get rapidly worse.

Can you fix it yourself?

The only safe things to try are the ones Canon suggests: switch the camera off and on, remove and re-insert the battery, and try a freshly formatted card. If the error clears and never returns, you were lucky.

If Err 20 keeps coming back, stop shooting. As the case above shows, a broken gear inside the shutter can damage neighbouring parts every time the camera tries to fire. A shutter replacement requires a complete teardown of the body and a factory-spec recalibration afterwards — work for a Canon repair lab, not a kitchen table.

How we repair it

A customer sent us his 6D Mark II a few months after the official warranty had expired. During a burst the camera had started throwing Err 20 and locking up, and by the time it reached us the error was almost constant.

As is our standard practice, we first assess whether the faulty component can be repaired rather than simply swapped — replacing parts blindly is the easy way out, not the right one. In this case, however, the broken gear had already damaged the other connected components of the shutter, so the entire shutter unit had to be replaced. After fitting the new unit our technician recalibrated the camera, cleaned it internally and tested every other function to verify full compliance with factory specifications — all included in the fixed price. The camera left the lab error-free and ready for hundreds of thousands of shots.

Price and turnaround

Service	Price
Shutter replacement, Canon EOS 6D Mark II	€250 (fixed)
Internal cleaning	Included
Final test & calibration	Included

The turnaround shown above is typical for this repair; your exact timing is confirmed in the free written quote and can vary with parts availability. Return shipping is a flat €20 by UPS to most EU destinations. Return shipping is a flat €20 most of the EU.

Ship your camera from most of the EU — diagnosis is free and every repair is covered by a 6-month warranty. See how it works.

See also our Sony A7 III shutter replacement — the same job on a mirrorless body, with the full set of bench photos.