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Ellie-dynamsoft merged 6 commits into from
Dec 12, 2025
Merged

update OCR guide and Chrome 142 FAQ #962

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cd0c362
update error message for code -2217
tony-xlh Dec 11, 2025
7c2dfd1
Clarify Local Network Access restrictions in Chromium 142 documentati…
lyzhang0113 Dec 12, 2025
39c6613
update note for ocr guide step 1
tony-xlh Dec 12, 2025
b23c4c3
Merge branch 'preview' of https://github.com/dynamsoft-docs/web-twain…
tony-xlh Dec 12, 2025
5f985a6
update OCR FAQ about data privacy
tony-xlh Dec 12, 2025
8bfb977
add link to online demo's code
tony-xlh Dec 12, 2025
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11 changes: 9 additions & 2 deletions _articles/extended-usage/ocr.md
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Expand Up @@ -33,7 +33,12 @@ Download [DynamicWebTWAINOCRResources.zip](https://download2.dynamsoft.com/dwt/D

It will copy an `ocr` folder to Dynamic Web TWAIN Service's [installation folder](/_articles/extended-usage/dynamsoft-service-configuration.md#installation-folder). The `ocr` folder contains the runtime and model files that are required to perform on-device OCR.

PS: You need to [install Dynamic Web TWAIN Service](/_articles/extended-usage/dynamsoft-service-configuration.md#installation-of-dynamic-web-twain-service) beforehand.

> [!NOTE]
> * You need to [install Dynamic Web TWAIN Service](/_articles/extended-usage/dynamsoft-service-configuration.md#installation-of-dynamic-web-twain-service) beforehand.
> * Since only Windows is supported for now, you have to do this on a Windows client for testing.



### Step Two - Write a Basic Document Scanning Page

Expand Down Expand Up @@ -440,6 +445,8 @@ Here is the complete code of the demo.
</html>
```

This complete code is different from the [online demo](#online-demo)'s code, which supports regional OCR. You can find the code for the online demo [here](https://download2.dynamsoft.com/Samples/DWT/Scan-Documents-and-Do-OCR.zip).

## FAQ

### What Languages are Supported?
Expand All @@ -458,7 +465,7 @@ Yes. You can specify which regions for OCR using the `rects` option of the [`rec

### Will My Document be Uploaded to a Remote Server?

No. The OCR process happens locally on your machine. No data is sent to any remote servers.
No. The OCR process happens locally on your machine. No data is sent to any remote servers. Also, we do not collect data for training AI.

### What is Searchable PDF?

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18 changes: 12 additions & 6 deletions _articles/faq/chromium-142-local-network-access-issue.md
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Expand Up @@ -7,7 +7,7 @@ keywords: Dynamic Web TWAIN, Error Troubleshooting, CORS, unknown address space,
breadcrumbText: Error message - Permission was denied for this request to access the unknown address space
description: CORS unknown address space
date: 2025-11-04 17:21:42 +0800
last_modified: 2025-11-26 15:46:00 +0800
last_modified: 2025-12-12 10:04:00 +0800
---

# Error Troubleshooting
Expand All @@ -19,7 +19,7 @@ last_modified: 2025-11-26 15:46:00 +0800

### Overview

Starting in **Chromium-based browsers v142+** (released Oct 28, 2025)—including Chrome, Edge, Brave, and Opera—Dynamsoft Web TWAIN Service may not work as expected due to new local-network security rules.
Starting in **Chromium-based browsers v142+** (released Oct 28, 2025)—including Chrome, Edge, Brave, and Opera—Dynamsoft Web TWAIN Service may not work as expected due to new **Local Network Access (LNA)** restrictions that limit requests **from public network locations to private and loopback network locations**.

### Symptoms

Expand All @@ -41,6 +41,8 @@ from origin 'https://your-domain.com' has been blocked by CORS policy:
Permission was denied for this request to access the `unknown` address space.
```

This error occurs because the web page is loaded from a public network origin (for example, `https://your-domain.com`) and is attempting to connect to a loopback network location (`127.0.0.1`), which Chrome now treats as a protected local network request.

---

#### Version-Specific Behavior
Expand All @@ -59,10 +61,14 @@ The observed behavior depends on Chromium browser version and Dynamic Web TWAIN

### Root Cause

Chromium 142 introduces a new [Local Network Access security policy](https://chromestatus.com/feature/5152728072060928) requirement.
Requests from web pages to loopback addresses such as `localhost` / `127.0.0.1` are blocked unless the user (or an admin policy) explicitly grants access.
Chromium 142 introduces and enforces a new [Local Network Access (LNA)](https://chromestatus.com/feature/5152728072060928) security model that restricts requests **from public network locations to private and loopback network locations**, requiring explicit user permission.

> [!NOTE]
> For background and design rationale, see Chrome’s Developer Blog: [New permission prompt for Local Network Access](https://developer.chrome.com/blog/local-network-access).

Under this model, **requests originating from a public network location** (such as a publicly hosted website) **to private or loopback network locations** (including localhost and 127.0.0.1) are blocked by default unless the user explicitly grants permission.

Because Dynamic Web TWAIN communicates with a local service, these restrictions can prevent normal operation.
Dynamic Web TWAIN relies on a locally installed service that listens on a loopback address. When a web application hosted on a public domain attempts to communicate with this service, Chrome categorizes the request as a **public-to-local** network request, which now requires explicit user consent.

### Resolution

Expand Down Expand Up @@ -166,6 +172,6 @@ Here are the details:

This design will be integrated in v19.3. For old versions, we can include an extra js file, which can be retrieved by contacting [support](mailto://support@dynamsoft.com).

## Other Causes
## Other Causes of Failure to Connect to the Service

There are other causes of service not being connected. You can find them in [another FAQ](/_articles/faq/service-prompting-to-install-repeatedly.md).
2 changes: 1 addition & 1 deletion _articles/info/api/appendix.md
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Expand Up @@ -63,7 +63,7 @@ description: Dynamic Web TWAIN SDK Documentation API Appendix Page
|-2207 | The Dynamic Web TWAIN Service installed on your computer is outdated and no longer works with the JavaScript code on the website |
|-2208 | The connection with the local Dynamic Web TWAIN Service encountered a problem and has been reset |
|-2209 | The HTML5 (Chrome&Firefox) edition does not support this method or property |
|-2217 | Missing dependent files for OCR. |
|-2217 | Missing dependent files for OCR Kit. |
|-2300 | Http upload error: the HTTP Server cannot empty |
|-2301 | Network error |
|-2302 | The result format is invalid |
Expand Down