Sony FDR-AX43A Not Recording

If your Sony FDR-AX43A not recording has you scratching your head, you're not alone. This is one of the most common frustrations owners run into. And it almost always has a dead-simple fix.

The camera is a solid piece of kit, but a few small things can stop it from capturing a single frame.

Per the SD Association standards, the AX43A requires a UHS Speed Class 3 (U3) card for reliable 4K recording at 100 Mbps. Anything slower can cause the camera to refuse to start. Let's walk through the most likely causes in order of probability.

Quick Answer

The Sony FDR-AX43A not recording is usually a simple fix. Check the record lock switch first. Then verify your SD card is U3 or faster.

Over 90% of cases are solved by these two checks.

If the button still does nothing, look at the mode dial. The camera may be in playback or photo mode. Switch it to video mode.

If you see an error message, note the exact wording. That points directly to the problem.

Still stuck? Move to the battery and heat checks. A low battery or overheating can block recording.

The fix is often just a fresh battery or a short cooldown. If none of these work, it's likely a firmware issue or a hardware fault.

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The Physical Record Button and SD Card Lock Switch

The most common reason the camera won't record is the simplest. The record button on the AX43A has a physical lock switch. It's a small sliding lever right next to the red record button.

If it's slid to the locked position, pressing the button does absolutely nothing.

Slide it to the unlock position. You'll feel a slight click. The button should now work normally.

Many users accidentally bump this switch while handling the camera or storing it in a bag.

The same goes for the SD card. The card itself has a write-protect tab on the left edge. If that tab is slid down to the "Lock" position, the camera will show a "Card Locked" error message and refuse to record.

Slide it up to unlock.

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If you've checked both switches and the camera still won't record, the issue is likely with the card itself. That's the next step. Similar recording issues can happen with other devices, and the same troubleshooting logic applies.

Our guide on Google Nest Cam Not Recording covers a similar process for a different camera.

The SD Card: Speed, Format, and Capacity

The AX43A is genuinely picky about SD cards. For 4K recording at 100 Mbps, you need a U3 card. Slower cards cause the camera to stop recording or refuse to start.

Here's a quick reference table.

If you're using a card that's too slow, the camera will show an error. Switch to a U3 card or drop down to a lower bitrate format in the menu. That's a temporary workaround, but a proper U3 card is the real fix.

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Format is another common gotcha. The camera needs the card formatted in its own menu, not on a computer. Go to MENU, then MEDIA SETTINGS, and select Format.

This erases everything on the card, so back up any footage first. The camera uses the exFAT file system for XAVC S and FAT32 for AVCHD. If you've formatted the card on a PC with the wrong system, the camera may not recognize it.

Capacity matters too. The AX43A officially supports up to 256 GB SDXC cards. Some firmware versions support 512 GB, but always check the manufacturer's specs.

Cards larger than 256 GB can cause intermittent recording failures. If you're using a card that's too large, try a smaller one.

Mode and Menu Settings That Can Block Recording

The camera has a mode button on the top. If it's in playback mode, it won't record. Press the MODE button to cycle through to recording mode.

The screen icon should show a red dot or a video camera. If you see a play symbol or a photo icon, you're in the wrong mode.

Menu settings can also block recording. Go to MENU, then REC/OUT SET, and check the File Format. Make sure it's set to a video format like XAVC S 4K or AVCHD.

If it's set to photo mode, the camera will only take stills.

Dual recording is another hidden setting. The AX43A can record in two formats simultaneously. This can cause conflicts if the secondary format isn't compatible with your card.

Try disabling dual recording in the menu. Go to REC/OUT SET, then Dual Rec, and turn it off.

If you've checked all the menu settings and the camera still won't record, there's a good chance the issue is a recording error that's been triggered by a corrupted file on the card. Format the card in the camera as a first step. If that doesn't fix it, try a different card entirely.

Battery, Overheating, and Power-Saving Limits

The camera stops recording if the battery is too low. It needs enough power to write the file and keep the lens steady. Replace the battery with a fresh one or plug in the AC adapter.

The NP-FV70A battery lasts about two hours of continuous recording, but that's in ideal conditions. Cold weather and heavy use can drain it faster.

Overheating is another issue. The AX43A has a thermal protection system. If the internal temperature gets too high, it stops recording to protect the sensor.

This is common in direct sunlight or when recording 4K for long periods. Let the camera cool down for 15 minutes in the shade. You can also turn off the LCD screen to reduce heat.

The 29-minute recording limit is a legal requirement, not a malfunction. In some regions, consumer cameras are capped at 29 minutes per clip for AVCHD recording. The camera stops automatically.

Press record again to start a new clip. For longer recordings, switch to XAVC S format, which doesn't have this limit.

If you're experiencing battery-related glitches, the same troubleshooting steps apply to other battery-powered devices. A fresh battery or a power reset often solves the problem. Our guide on Wyze Cam Outdoor Battery Problems covers similar battery troubleshooting for a different camera.

Deeper Issues: Firmware, Hardware, and When to Call Sony

If you've checked the physical switches, the card, the menu settings, and the battery, the issue is probably deeper. Firmware bugs can cause intermittent recording failures. As of 2026, the latest firmware version for the AX43A is available on Sony's official support page.

Updating the firmware is straightforward. Download the file to your computer. Copy it to a formatted SD card.

Insert the card into the camera and navigate to MENU, then SETUP, then Version. Follow the on-screen prompts. The update takes about 10 minutes.

Hardware faults are rarer but they happen. A stuck record button, a damaged card slot, or a failing main board can all stop recording. If the camera is still under warranty, contact Sony support.

If it's out of warranty, a reputable camera repair shop can diagnose the issue. Expect to pay between $100 and $300 for common repairs.

Before you give up, try a factory reset. Go to MENU, then SETUP, then Reset. This clears all your custom settings.

It can fix software glitches that aren't obvious from the menu. After the reset, set the camera to a basic video mode and try recording again.

If none of these steps work, the camera likely has a hardware fault. This is rare, but it's worth knowing when to stop troubleshooting and start calling for help. The same approach applies to other devices that won't record properly.

Our guide on EufyCam 3 Not Recording covers a similar diagnostic process for a different camera system.

How to Keep It From Happening Again

Once you've got the camera recording again, a few simple habits can prevent future issues. First, always format your SD card in the camera before a shoot. This clears any corrupted files and ensures the file system is compatible.

Second, keep a spare U3 card in your bag. If the main card fails, you have a backup. Cards are cheap compared to missing a once-in-a-lifetime shot.

Per SD Association guidelines, U3 cards are rated for 30 MB/s minimum write speed, which is plenty for the AX43A's 100 Mbps 4K stream.

Third, turn off the camera when you're not using it. Leaving it in standby mode drains the battery slowly. A low battery can cause recording errors.

It also keeps the internal temperature down, reducing the risk of overheating.

Fourth, update the firmware regularly. Sony releases patches that fix bugs and improve stability. Check the support page every few months.

Keeping the firmware current is a simple way to avoid common glitches.

Finally, handle the record button with care. The lock switch is easy to accidentally slide. Get in the habit of checking it before every shoot.

A quick glance can save you a lot of frustration.

General troubleshooting principles apply across many devices. Our guide on Google Nest Cam Troubleshooting covers a similar systematic approach for a different camera.

Frequently Asked Questions

Why does my Sony AX43A say "Card Locked" when the tab is unlocked?

The write-protect tab on the SD card may be stuck or dirty. Remove the card and slide the tab back and forth a few times. If the error persists, the card's contacts may be dirty.

Clean them with a soft, dry cloth. If that doesn't work, try a different card.

Can I use a Class 10 card for 4K recording?

No. The AX43A requires a U3 card for 4K at 100 Mbps. A Class 10 card only guarantees 10 MB/s write speed, which is too slow.

The camera will refuse to record or will stop mid-clip. Use a U3 card or switch to AVCHD format.

How long does the AX43A record before overheating?

It depends on the ambient temperature. In normal conditions (around 70°F), you can record 4K continuously for about 30 minutes before the camera gets warm. In direct sunlight or hot weather, that time drops to 15 minutes.

Let the camera cool down before starting again.

Why does my camera stop recording at exactly 29 minutes?

This is a legal requirement for consumer camcorders in some regions. The camera stops at 29 minutes to avoid being classified as a video camera for import duties. Press record again to start a new clip.

Switch to XAVC S format to avoid this limit.

How do I reset my Sony AX43A to factory settings?

Go to MENU, then SETUP, then Reset. Confirm the reset. This clears all custom settings, including Wi-Fi passwords and date/time.

After the reset, set the camera to a basic video mode and test recording. It's a good first step for persistent issues.

When should I send my camera for repair?

If you've checked the lock switch, tried a different U3 card, formatted the card in the camera, updated the firmware, done a factory reset, and the camera still won't record, it's likely a hardware fault. Contact Sony support or an authorized repair center. The same decision logic applies to other cameras with recording problems.

Our guide on Reolink Duo 3 Recording Problems follows a similar troubleshooting path.