How to Fix the “Unable to select TWAIN source” Error for the Canon CanoScan LiDE 25 Scanner in Windows 10

Last Updated on 29.06.2026 by DriverNew

Canon CanoScan LiDE 25 is an old but still useful scanner. The problem is that Canon does not provide a separate official Windows 10 driver for this model. Therefore, on Windows 10 x64, the scanner often works only after installing the Windows 7 x64 driver.

One common error when starting a scan is “Unable to select TWAIN source”.

Usually, this error means that the scanning program cannot find the scanner’s TWAIN driver. Below are several methods that can help fix this problem.

Before You Start Checking

First, make sure the scanner is connected directly to the computer and not through a USB hub. If the computer has a USB 2.0 port, it is better to use that port. It is usually black inside. Older scanners sometimes work unreliably through USB 3.0 ports, which are often blue.

It is also recommended to restart the computer after installing the driver or changing system settings.

Method 1. Add the TWAIN Driver Path to the Path Variable

Sometimes the driver is installed, but Windows or the scanning program does not know where its files are located. In this case, you can manually add the path to the driver folder.

Important: do not delete existing entries in the Path variable. You only need to add new entries.

1. Press Win + R. The Run window will open.
2. Enter the command sysdm.cpl and click OK.
3. Open the Advanced tab.
4. Click the Environment Variables… button.
5. In the lower System variables section, find the Path entry.
6. Select Path and click Edit….
7. Click New and add this entry: C:\Windows\twain_32\CNQL25
8. Click New again and add the second entry: C:\Windows\twain_32
9. Click OK in all open windows to save the changes.
10. Restart the computer.

After restarting, try scanning again.

Method 2. Reinstall the Driver in Compatibility Mode

If the first method did not help, the driver may have been installed incorrectly. In this case, it is better to remove the old driver and install it again.

1. Download the official Canon driver for Windows 7 x64. The file may be named lide25vst6411011aen.exe.
2. Disconnect the scanner from the computer.
3. Right-click the downloaded driver file and select Properties.
4. Open the Compatibility tab.
5. Select the checkbox next to Run this program in compatibility mode for:.
6. In the list, select Windows 7.
7. Select the checkbox next to Run this program as an administrator.
8. Click OK.
9. Run the driver installation and follow the setup wizard instructions.
10. After the installation is complete, restart the computer.
11. Connect the scanner to a USB port and wait until Windows detects the device.

If Windows does not detect the scanner, try another USB port and another USB cable.

Method 3. Use NAPS2 Instead of the Old CanoScan Toolbox Program

The old CanoScan Toolbox program may work unreliably on Windows 10 x64. Instead, you can use the free NAPS2 program.

Important: NAPS2 does not replace the scanner driver. The Canon driver must still be installed. NAPS2 simply uses the installed TWAIN or WIA driver for scanning.

1. Download and install NAPS2 from the developer’s official website.
2. Open NAPS2.
3. Click Profiles.
4. Click New.
5. In the driver selection field, choose TWAIN Driver.
6. Click Select Device.
7. Select CanoScan LiDE 25 from the device list.
8. Click OK to save the profile.
9. Return to the main NAPS2 window and click Scan.

If the scanner does not appear in the device list, the problem is most likely not with NAPS2, but with the driver or the scanner connection.

Alternative Option: VueScan

If the Canon driver does not install or the TWAIN error does not go away, you can try VueScan. This is a separate scanning program with built-in support for many older scanners, including Canon CanoScan LiDE 25.

The advantage of VueScan is that in some cases it lets you use the scanner without manually configuring the TWAIN driver in Windows. The disadvantage is that the program is paid, although a trial version is usually available.

What to Do If the Error Remains

• Check whether Windows sees the scanner in Device Manager.
• Try connecting the scanner to another USB port.
• Do not use a USB hub or extension cable.
• Reinstall the driver as an administrator.
• After installing the driver, be sure to restart the computer.

Conclusion

The “Unable to select TWAIN source” error for Canon CanoScan LiDE 25 in Windows 10 is usually related to the scanning program being unable to find the TWAIN driver. Most often, installing the Windows 7 x64 driver, adding the TWAIN folder to the Path variable, and using a modern scanning program such as NAPS2 help solve the problem.

If these methods do not help, the easiest option is to try VueScan, because this program has its own support for Canon CanoScan LiDE 25.