topic Re: No scanning with CanoScan LiDE 400 on new iMac with Mac OS Tahoe 26.3 in Scanners

No scanning with CanoScan LiDE 400 on new iMac with Mac OS Tahoe 26.3

CatOut — Sat, 04 Apr 2026 21:54:44 GMT

My new iMac running Mac OS Tahoe 26.3 is unable to scan with my new CanoScan LiDE 400.

I downloaded and installed Canon IJ Scan Utility Lite (msul-mac-4_2_1-ea21_3.dmg).
I downloaded and installed the driver setup (mac-lide400-1_2-mcd.dmg).
I added the scanner to my Printers and Scanners and the Mac recognizes the device.
I toggled the lock/unlock switch multiple times and left it in the unlock position.
I pulled out and securely reattached the USB cable multiple times. I'm using an Apple USB-C adapter to plug it into my Mac.
I restarted the Mac multiple times.
The gears inside the scanner do a preliminary roll up when it detects power.

The Canon IJ Scan Utility Lite window appears, but only allows the settings to be changed. There is no "Scan" button after I choose one of the visible selections, it just brings me back to this window.

I tried using Image Capture. It recognizes the scanner. But it doesn't let me Overview (preview) or Scan. It also thinks the scanning bed is HUGE. When "US Letter" is selected it appears as a tiny rectangle in the upper left-hand corner. When Custom size is selected and reshaped, it thinks the page size is 550 x 777 inches!

Then I tried VueScan. No luck there either. It thinks the scanner is locked. It isn't.

I need some help. I'm ready to pack this thing up and return it -- three strikes and you're out. But I still need a scanner. What's my next step?

Re: No scanning with CanoScan LiDE 400 on new iMac with Mac OS Tahoe 26.3

jrhoffman75 — Sun, 05 Apr 2026 11:12:57 GMT

Give VueScan support a call or email.

Re: No scanning with CanoScan LiDE 400 on new iMac with Mac OS Tahoe 26.3

CatOut — Sun, 05 Apr 2026 16:06:55 GMT

Reached out to VueScan. Ed suggested that the scanner may be broken.

Re: No scanning with CanoScan LiDE 400 on new iMac with Mac OS Tahoe 26.3

jrhoffman75 — Sun, 05 Apr 2026 18:20:39 GMT

New, so under warranty.

Re: No scanning with CanoScan LiDE 400 on new iMac with Mac OS Tahoe 26.3

Stephen — Sun, 05 Apr 2026 20:12:43 GMT

Welcome to the Canon Community!

I see you’ve been working through this with the community and even reached out to VueScan. Before you pack it up, I’d like to offer some advanced guidance. Here on social media, we aren't specifically trained for technical support; however, I’ve handled many cases similar to this, and I suspect we’re looking at a power delivery issue rather than a broken scanner.

A Note on Power & "Locked" Errors:

The CanoScan LiDE 400 draws its entire power supply through the USB cable. The "scanner is locked" error is a classic symptom of the motor trying to initialize but not receiving enough "juice" from the port to move. Standard USB-C adapters or unpowered hubs can often be "flakey" with power delivery. Personally, I have found that using a powered USB-C hub (brands like Anker or UGREEN are reliable favorites in this community) almost always resolves these communication and initialization errors immediately.

The "Fresh Start" Protocol:

To ensure the drivers (specifically the ICA driver used by Image Capture and VueScan) are correctly registered on macOS Tahoe:

Disconnect the scanner from your iMac.
Visit our Official Setup Page to download the latest software package.
Follow the prompts and only plug the scanner back in when the software specifically tells you to.

Next Steps:

If you try a powered connection and a fresh install but the error persists, it may indeed be a hardware fault as Ed suggested. While I’m happy to help you get to the right place here on social, our phone team is best equipped to perform a final diagnostic. Since your unit is new, please register your scanner and then call 1-800-OK-CANON (800-652-2666), weekdays from 9am to 6pm (ET). They can determine the best path forward, whether that involves further troubleshooting or a warranty exchange.

Re: No scanning with CanoScan LiDE 400 on new iMac with Mac OS Tahoe 26.3

CatOut — Mon, 06 Apr 2026 02:36:00 GMT

Stephen, would a Thunderbolt USBC-to-C cable work instead of the supplied Canoscan USBC-to-A with an A-to-C adaptor / hub?

Re: No scanning with CanoScan LiDE 400 on new iMac with Mac OS Tahoe 26.3

Stephen — Mon, 06 Apr 2026 12:12:42 GMT

The supplied cable will absolutely work - it just has to be plugged directly into your iMac or a powered USB hub, like below:

Powered USB-C Hubs

Re: No scanning with CanoScan LiDE 400 on new iMac with Mac OS Tahoe 26.3

CatOut — Mon, 06 Apr 2026 22:55:02 GMT

"powered USB-C hub (brands like Anker or UGREEN)" The powered USB-C hubs I'm looking at on Amazon don't seem to have powered USB-A ports; just one USB-C port has a lightning bolt. What am I missing? How is the USB-C plug on the adaptor getting so much wattage from the USB-C port on the back of the iMac?

Re: No scanning with CanoScan LiDE 400 on new iMac with Mac OS Tahoe 26.3

CatOut — Tue, 07 Apr 2026 20:21:57 GMT

Stephen, in regards to a powered hub, according to the Canon scanner specs, it only draws 4.5W. According to Apple specs, the minimum wattage supplied from a USB-C/Thunderbolt port on the iMac is 15W. That cable should not need anything other than a USB-A to USB-C adaptor, and the one I'm using is an Apple adaptor.

Re: No scanning with CanoScan LiDE 400 on new iMac with Mac OS Tahoe 26.3

Stephen — Tue, 07 Apr 2026 20:57:41 GMT

Please contact support for further assistance. They are available at 1-800-652-2666.