Could not open the twain source photoshop windows 7

TWAIN has been the main technology used for scanning in Photoshop for many versions. However, it is not always updated for new operating systems. Therefore, it may work less reliably than other scanning solutions, such as third-party utilities such as VueScan, the scanner software that comes with your scanner, or other scanning technologies. These third-party utilities are dedicated scanning solutions, and they are more appropriate for critical or high-volume scanning.

If you use a third-party scanning application, save your scanned images as TIFF files, then open them in Photoshop.

Note: To use any scanner technology, you need to install a scanner driver. This will probably be installed via your operating system, but you may need to contact your scanner manufacturer, especially for older scanners.

Canon Scanner – Unable to open TWAIN source

I have a Canon CanoScan 4400F Scanner and the other day I was unable to get it to work.  I use the Canon software CanoScan Toolbox to operate the scanner and when trying to scan I was getting the following error message:


CanoScan Toolbox
Unable to open TWAIN source
Please check connection
Then re-start Toolbox

Searching the Internet for this problem turned up several people having the same problem and several solutions which looked like they may or may not work.  One of the recommended solutions was to make sure a certain folder path is in your PATH environment variable.  As it turned out this was the problem, so here is how to add that path back into your environment variables.

First, determine the correct path to add into the PATH environment variable.  Look in C:Windowstwain_32 and there should one other folder in there.  In my case it was  named CNQ4803.


This is the path that is needed to be added into the PATH environment variable.



Now, follow these instructions to get to the dialog to modify the PATH environment variable.

Control Panel > System > and then choose Advanced System Settings in the left hand column.


This will bring up the System Properties dialog (it should already be on the Advanced tab).


At the bottom of this dialog is an Environment Variables button.  Clicking this button will bring up the Environment Variables dialog.


In the bottom panel, scroll until you find the variable named Path.  Select this one and then hit the Edit… button to bring up the Edit System Variable dialog.


In the Variable value text box, scroll all the way to the right and then add in the path C:Windowstwain_32CNQ4803 that was determined earlier.  Make sure to separate this value with a preceding semi-colon.  And also be careful not to make any other changes to this value.

Now OK your way out of all of the dialogs and CanoScan Toolbox will now work as expected.

Recently I replaced my laptop and one of the important things that I needed to get working on it was my Canon LiDE25 scanner that I used for tasks. Each time I replace my laptop (which happens frequently enough) I encounter the same problem with this Canon scanner, so I thought that I would share with all of you how to solve this issue because it can be a bit annoying. BTW you can download the Canon Scanner software on their site. Just as an aside, I need to do this on my Windows 10 and Windows 11 computers too!

Below is the error message that I always get:

Unable to open TWAIN source
Please check connection
Then re-start Toolbox

The problem is that the TWAIN drivers are not within the computer system variables path.

How to Solve the Canon Scanner – Unable to Open TWAIN Source Error

This problem took a while for me to find and solve . But one you know what the problem is the solution is easily fixed.

What I do first is open the Control Panel.

Next I click System and Security.

Then I click System.

Next, I click Advanced system settings.

Then, I click Environment Variables…

Then I scroll down on the system variables and find the Path, highlight it and then click Edit.

Next I add the path name for my TWAIN driver to the Path system variable. In this case, it is c:windowstwain_32CNQL25. Lastly, I click OK three times to return to the Control Panel, and then I exit the Control Panel.

Finally, I restart the CanonScan Toolbox. Now my Canon scanner works without any issues and the same should be true with your scanner.

I hope this solved your problems with your Canon Scanner. if you have questions you can always tweet me @garthmj. I will do my best to get back to you once I see it.

Back again with another commonly-asked question of our Technical Support Team.

“I’m trying to scan a document, but I keep getting a TWAIN error.”

Issues with the TWAIN driver indicate that the computer isn’t recognizing the scanner driver, and Scan Workstation is reporting a problem. However, TWAIN driver errors are not caused by the Scan Workstation.

A TWAIN driver is software that handles communication between a PC and a scanner.

Updates or reboots to the scanner could be the reason the scanner is no longer recognizing the TWAIN driver. To fix this problem, you should try the following:

  • Try rebooting the scanner, or unplug the scanner from the workstation and plug it back in.
  • Open the TWAIN driver you installed with your scanner and check the scanner settings.
  • Upgrade your TWAIN driver from the manufacturer’s website.
  • Check whether other programs on your PC can scan.
  • Uninstall and reinstall the scanner software.

If none of these remedy the TWAIN error, contact the scanner’s manufacturer for device-specific fixes.

I recently upgraded from Photoshop CS5 to Photoshop CC and it has been a great improvement overall.  However, I still have my old Canoscan LIDE 25 scanner that uses TWAIN.  If you remember, this involved a bit of tweaking when I went to get it to work with CS5  and CS6.

At any rate, here’s how you get your Canon Canoscan LiDE25 (or other TWAIN scanner) working with Photoshop CC on Windows 7:

  1. Install the CanoScan LIDE 25 driver.  You can find that on the Canon download page (or download it here locally if they ever stop updating it)
  2. Adobe does not have TWAIN support installed in Photoshop by default anymore.  Instead, you must download their Optional Plugin pack.  It’s important to note that you download the CS6 plugin pack for CS6 or CC editions.  Also note, the TWAIN support only works on the 32-bit version of Photoshop.  It will NOT work on 64-bit versions of Photoshop.
    1. Download the Optional pack
    2. Close Photoshop
    3. Install the option pack by copying it in the right plugin directory for your 32-bit version of Photoshop (see their website for the right directory)
    4. Open Photoshop (32-bit version)
  3. So, you installed the scanner driver and Photoshop is updated.  I open Photoshop and go to File->Import->Canoscan LiDE25.  Sadly, I then get this error message: “

    Could not open the TWAIN source

    Make sure there is a valid source 

    for your scanner in the TWAIN 


     found in the 

    Window Directory



    , what is going on?  I try running the CanoScan

    Toolbox and when I copy/PDF and hit the ‘Copy’ or ‘Scan’ button, I get this error message:

    Unable to open TWAIN source. Please check connection then re-start Toolbox.

    However, if I use a 3rd party tool like


    – it is able to capture scans just fine.  So I know the scanner is physically working.

  4. I found this badly aged/broken blog entry, but it describes the solution:
    1. Go to your c:Windowstwain_32 directory
    2. You should see a sub-folder with a number/letter combination,  Mine is: C:Windowstwain_32CNQL25
    3. Add that to your system path variable
      1. Right-click on Computer -> Properties -> Advanced system settings -> Advanced -> Environment Variables
      2. In the bottom System variables scroll-box, find the ‘Path’ variable
      3. Click edit and go to the far right of the ‘Variable value:’ field. Enter the directory to the end of the list, separating it from previous entries by a ‘;’.  Google adding a directory to system path in Windows if you need more help.
        i.e. ;C:Windowstwain_32CNQL25
      4. Save and close the system settings
  5. Restart Photoshop 32-bit – and you should have success!

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[For the Windows 10 version see the updated article here]

Epson 1200U ScannerLike myself, many folks still own the popular Epson 1200 Photo or 1200U scanner. Likewise, many of us have transitioned to Vista or Windows 7. Unfortunately, Epson, in their “wisdom” has failed to provide working Vista or Windows 7 drivers for these older scanners—preferring no doubt that we all go out and purchase a new scanner instead. It’s called “planned obsolescence,” no doubt the most annoying trend in the hardware and software industries.

Fortunately, there is a workaround that preformed well in my case. This involved using the most recently available Windows XP Twain drivers installed under Windows 7 using Windows XP compatibility mode. For Vista users the process should follow the same principles.

[Edited: If you are using a 64-bit version of Vista or Windows 7, you may wish to attempt the method outlined by Equinox in the comments to this post.]

Step 1: Download the most recent version of the Epson Twain drivers from the Epson site. At the time of writing this was TWAIN Driver v5.53A (for Windows XP, Windows 2000, Windows Me, Windows 98 – epson10245.exe – 4.6MB – posted on 02/25/02). The file bundle is a self-extracting Zip archive. Note the location of the download.

Step 2: Locate the file (epson10245.exe) that you have downloaded and extract it by double-clicking the file. By default the auto-extractor will attempt to install its files in C:epsonepson10245. You may specify a different location if you wish. NOTE: When you progress to the screen below, UNCHECK the section “When Done Unzipping Run: Setup.exe.” We will want to handle that differently below.

Epson 1200U Twain Driver - WinZip Self-extractor [epson10245.exe]

Step 3: Navigate to the directory C:epsonepson1024, or your alternative location if you selected different directory for extraction.

Step 4: Locate the file Setup.exe. Right-click on it and select Properties.

Step 5: Switch from the General to the Compatibility tab.

Step 6: On the Compatibility tab, under “Compatibility mode” check the box for “Run this program in compatibility mode for:” and select Windows XP (Service Pack 2) from the dropdown menu. Select Apply on the bottom right, then OK.

Epson 1200U Twain Driver - Setup.exe Properties

Step 7: Double click on Setup.exe to launch the installer and proceed through the installation.

After the installation has completed you should be able to find the driver options available in Photoshop under File –> Import –> EPSON TWAIN 5 and/or WIA-Epson Perfection1200.

Hopefully, now you can get another lifetime out of that old hardware before consigning it to the landfill.

Best of luck,








Written by Jane