What Canon ERR 20 Means
If you are searching for canon err 20 how to fix, you are likely dealing with a camera that will not shoot normally because the shutter system, mirror assembly, or communication path has failed.
Canon uses error codes to flag specific internal problems, and ERR 20 usually points to a mechanical or electrical fault that needs careful diagnosis.
This error can appear on EOS DSLR bodies and may show up intermittently or persist until the camera is serviced.
The tricky part is that several different issues can trigger the same code, which is why a methodical approach matters.
Common Causes of ERR 20
Canon ERR 20 is most often associated with one of these problems:
- Shutter unit wear or failure
- Mirror box or mirror mechanism sticking
- Lens communication errors between the camera body and lens
- Battery power instability
- Contamination or obstruction inside the camera body
- Firmware or electronic control faults
Some cameras display ERR 20 after a dropped impact, after years of heavy use, or when a lens or accessory has poor electrical contact.
In other cases, the fault is temporary and related to low power or a stuck mechanism.
First Steps to Try Before Service
Before assuming the camera needs repair, use these basic checks.
They are low-risk and can help you rule out simple causes.
Power cycle the camera
Turn the camera off, remove the battery, and wait at least 60 seconds.
Reinsert a fully charged battery and turn the camera on again.
A full reset can clear a temporary control glitch.
Remove and inspect the lens
Detach the lens and inspect both the lens mount and body contacts for dirt, moisture, or bent pins.
Reattach the lens firmly and test the camera again.
If the error started after switching lenses, test with a different Canon EF or EF-S lens if available.
Check the battery and card
A weak battery can cause unstable behavior in camera electronics.
Use an official or known-good battery and, if possible, format the memory card in-camera after backing up files.
While the card usually does not directly cause ERR 20, eliminating card-related issues is part of good troubleshooting.
Try the camera without accessories
Remove grips, flashes, remote triggers, battery grips, and third-party adapters.
External accessories can interfere with communication or power delivery, especially on older DSLR bodies.
How to Fix Canon ERR 20 Step by Step
When you want a practical answer to canon err 20 how to fix, the best sequence is to isolate whether the problem is mechanical, electrical, or accessory-related.
1. Reset the camera settings
Use the camera menu to reset shooting settings and custom settings to default.
A settings reset will not repair a broken shutter, but it can remove configuration issues that complicate troubleshooting.
2. Clean the lens contacts
Use a clean, dry microfiber cloth to gently wipe the metal contacts on the lens and camera mount.
Do not use liquid cleaners unless Canon support or a qualified technician recommends them.
Poor contact can interrupt lens-body communication and mimic a hardware fault.
3. Test with a different lens
If the camera works with one lens but not another, the lens may be causing the issue rather than the body.
Canon EF mount lenses contain electronic contacts and aperture control hardware, and a failing lens can sometimes trigger ERR 20-like behavior.
4. Listen for abnormal shutter or mirror movement
When you press the shutter button, listen closely.
A healthy DSLR typically produces a consistent mechanical sequence.
Grinding, clicking, partial movement, or no movement at all can indicate a shutter mechanism or mirror assembly problem.
5. Check for physical obstruction
Look carefully inside the lens mount area with good lighting.
Dust is normal, but do not insert tools into the body.
If the mirror appears stuck or the shutter curtains do not look normal, stop further testing to avoid additional damage.
When the Shutter Mechanism Is the Real Problem
In many Canon DSLR cases, ERR 20 is linked to shutter failure.
The shutter is a high-wear part, and repeated firing eventually causes wear in the blades, springs, or drive components.
Professional repair may involve replacing the shutter assembly, which is usually not a user-serviceable job.
Signs that point toward a shutter-related fault include:
- The camera fails after a high shutter count
- The error occurs at the moment of exposure
- The mirror or shutter sounds irregular
- The camera works briefly, then errors again
If your camera has thousands of actuations and ERR 20 is recurring, the shutter mechanism is a strong suspect.
Could Firmware Help?
Firmware updates can sometimes improve camera stability or compatibility with newer lenses and accessories.
While a firmware update is not a common cure for ERR 20, it is worth checking Canon’s official support page for your exact model.
Install only firmware intended for your camera body, and follow Canon’s instructions exactly.
If the camera cannot operate reliably, do not attempt updates unless the body can remain powered through the entire process.
Signs You Need Professional Repair
Some ERR 20 cases can be solved by cleaning contacts or changing lenses, but many require a technician.
Seek service if any of the following apply:
- The error appears immediately on startup
- The error persists with multiple lenses and batteries
- The mirror is stuck or the shutter does not cycle
- The camera was dropped or exposed to moisture
- The camera shows repeated errors after reset
Canon service centers and qualified camera repair shops can test the shutter, mirror box, main board, and internal connectors.
They may also check whether the body needs calibration after replacement parts are installed.
How to Prevent Canon ERR 20 in the Future
Even if you resolve the current problem, a few habits can help reduce the chance of seeing ERR 20 again.
- Use fully charged, genuine batteries
- Keep lens and body contacts clean
- Store the camera in a dry, dust-controlled environment
- Avoid forcing lens mounts or accessories
- Service the camera periodically if you shoot heavily
- Protect the body from impact and vibration
For high-volume shooters, regular maintenance is especially important.
Shutter wear is normal over time, and preventive servicing can be less expensive than waiting for a complete failure.
What to Tell a Repair Technician
If you hand the camera to a repair shop, describe exactly when the error appears.
Helpful details include the lens used, battery type, whether the camera was dropped, and whether the error happens during startup, autofocus, or exposure.
The more specific you are, the faster the technician can isolate the issue.
For example, mention whether the camera:
- Shows ERR 20 with every lens or only one
- Works after battery removal and returns later
- Makes unusual mechanical noises
- Has recently experienced heat, moisture, or impact
That information can help distinguish a simple contact issue from a shutter or mirror-box repair.
Bottom Line on Canon ERR 20
If you are looking for canon err 20 how to fix, start with the simplest checks first: battery, lens contacts, lens swap, and accessory removal.
If the error remains, the cause is often a shutter or mirror mechanism fault that requires professional repair.
A careful sequence of troubleshooting can save time, reduce unnecessary service costs, and help you decide quickly whether the camera is safe to use or ready for a Canon technician.