How to fix "Error: Could not connect to the scanner" in Adobe's Acrobat Reader

Authored by: Support.com Tech Pro Team

1. Introduction

To fix the problem, try the steps below in the order. After each step, check whether the problem is resolved; if not, follow the next step.

Check if the device is connected physically:
Check for the cables for e.g., USB cable, LAN cable etc. used to connect the scanner. Disconnect and reconnect the cables to make sure the connections are proper.
Make sure the scanner is switched on and is not showing any error message on its display (if any). In case of any error or if the scanner is stuck at some operation, restart the scanner.

Windows can have both TWAIN and WIA drivers installed. Similarly, Macintosh can have both TWAIN and ICA drivers. Try to scan with any other scanner driver alternative (ICA, WIA or TWAIN) in case one doesnâ€™t work.
On Windows: Select any of TWAIN and WIA drivers on the scanner selection screen in Acrobat as shown in the screenshot below.

On Mac: Select any of TWAIN and ICA drivers on the scanner selection screen in Acrobat as shown in the screenshot below.

Verify if the scanner works with any other application:
There are some built-in and third-party applications are available for Windows and Macintosh with which you can try to use the scanner:
For Windows, there is a software called TWACKER , a free TWAIN scanner driver test utility. It is available for free. Just download and install it to see if your scanner is working or not.
For OS X, there is a pre-installed Image Capture Application utility which can be used to check if the scanner is working or not.
Alternatively, If you have any other application installed which uses scan functionality then you may use the same to test that scanner is working as expected with that application.
If the scanner doesnâ€™t work with any application, then this confirms the fact that that scanner is not functioning properly and you may contact the scanner manufacturer for the issue.

Restart system with start-up items disabled:
Some applications can cause system errors or freezes when running concurrently with Adobe Acrobat. Before starting Acrobat, disable other applications, including startup items (items that start automatically with Windows).
To disable startup items in Windows, do the following:
Quit all applications.
Choose Start > Run. Type msconfig in the Open box, and then click OK.
In the System Configuration Utility dialog box, click the Startup tab, and then select Disable All.
Click OK, and then restart Windows.
To re-enable the startup items, do the following:
Choose Start > Run. Type msconfig in the Open box, and then click OK.
In the System Configuration Utility dialog box, click the Startup tab, and then select Enable All.
Click OK, and then restart Windows.

Install latest scanner drivers, and then restart the system:
If a TWAIN file is missing or damaged, then Acrobat returns an error message when you try to scan using the TWAIN interface. Reinstalling the scanner driver replaces the TWAIN file.
To reinstall the driver, delete all files and folders that begin with Twain (for example, "Twain_32.dll") in the Windows or Winnt folder. Then, restart Windows, and then install the latest scanner driver as per the manufacturer's instructions or steps mentioned here.