Thanks for posting on our forum!
Firstly, how did your WIA Error handler fail to display with Windows scan app? Was there any error messages poping up when you configure them together?
Based on your description, I think your issue tends to be a hardware related issue which is beyond our forum's scope. I strongly suggest you to directly contact your vendor, they should know the requirements for installing Error Handler Extension with WIA drive. Besides, I am going to check with my colleagues who work for Windows products like Windows scan app, to see if there is any limitation with Error Handler Extension of WIA drive.
Thanks for your support! Besides, would you please help me Accept Answer. An accepted blog can be put on top of our forum, so that people who have a similar issue can get access to their solution more quickly. I would really appreciate it if you could support my work.
If the Answer is helpful, please click "Accept Answer" and upvote it.
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Thanks for your reply!
After research, your issue belongs to windows drive forum and I have changed the tag for you. Our engineer specialized in this topic will come to help you in a minute.