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When using browsers based on Chromium version 142 (released on October 28th, 2025) or later (including but not limited to Edge, Brave, and Opera), the Dynamsoft Web TWAIN Service installation cannot be detected, prompting the Dynamsoft Web TWAIN Service installation modal. Installing the service does not fix the issue.
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When using Chromium-based browsers version 142 or later (released on October 28th, 2025), including Chrome, Edge, Brave, and Opera, the Dynamsoft Web TWAIN Service may fail to function properly:
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You may also encounter the following error message in the browser console:
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- Phenomenon 1: the browser prompts users to download the service installer even though it is already installed.
- Phenomenon 2: the initialization succeeds, but scanning or loading images results in blank images.
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Open the browser console (press F12, then go to the Console tab), you should see the following error message:
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```shell
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Access to fetch at 'https://127.0.0.1:18623/fa/VersionInfo?ts=1761893667670' from origin 'https://your-domain.com' has been blocked by CORS policy: Permission was denied for this request to access the `unknown` address space.
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```
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### Cause
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In Chromium 142 Google introduced a new Local Network Access security policy. Requests from web pages hosted within iframes to local addresses such as 127.0.0.1 or localhost get blocked unless explicit permission is granted.
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In Chromium 142 Google introduced a new [Local Network Access security policy](https://chromestatus.com/feature/5152728072060928). Requests from web pages to local addresses such as 127.0.0.1 or localhost get blocked unless explicit permission is granted.
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This affects the Dynamic Web TWAIN Service which relies on local services for communication.
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### Solution
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### Resolution
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<divclass="multi-panel-switching-prefix"></div>
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***Step 1: (For All End Users)***
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-[Quick Solution for End Users](#Quick Solutions for End Users)
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-[Solutions for Developers](#Solutions for Developers)
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- Navigate to your Dynamic Web TWAIN web interface
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<divclass="multi-panel-start"></div>
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- Click the lock icon (or settings icon) next to your site URL in the browser’s address bar.
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**Enable Local Network Access**
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Make sure your website has Local Network Access enabled.
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- Ensure that **Local Network Access** is enabled.
30.[How to debug on Dynamic Web TWAIN online demo?](/_articles/faq/debug-on-online-demo.md)
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31.[Dynamic Web TWAIN prompts the .deb installer for Windows](/_articles/faq/incorrect-installer-for-windowsARM64.md)
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32.[Why am I unable to load the TIFF file into Dynamic Web TWAIN?](/_articles/faq/unable-to-load-4-bit-tiff.md)
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33.[Error message - Permission was denied for this request to access the unknown address space](/_articles/faq/chrome-142-local-network-access-issue.md)
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33.[Error message - Permission was denied for this request to access the unknown address space](/_articles/faq/chromium-142-local-network-access-issue.md)
> "Local network access permission is not granted" is a **newly developing issue**
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1. The local network access permission is not granted (required starting Chromium 142). See [Chromium local network access issue](/_articles/faq/chromium-142-local-network-access-issue) for details and corrective action.
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1. The local network access permission is not granted (required starting Chromium 142).
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2. The Dynamic Web TWAIN Service (previously called "Dynamsoft Service") is not installed properly.
1.Check the service's [installation folder](/_articles/extended-usage/dynamsoft-service-configuration.md#installation-folder) and make sure you have [the correct files](/_articles/extended-usage/dynamsoft-service-configuration.md#related-files-and-folders){:target="_blank"}.
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1. See [Chromium local network access issue](/_articles/faq/chromium-142-local-network-access-issue.md) for details and corrective actions.
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2. Check `Local Services`and make sure the Dynamic Web TWAIN Service is listed and Running.
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2. Check the service's [installation folder](/_articles/extended-usage/dynamsoft-service-configuration.md#installation-folder)and make sure you have [the correct files](/_articles/extended-usage/dynamsoft-service-configuration.md#related-files-and-folders){:target="_blank"}.
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3. On IE, go to `Internet Options` --> `Security` tab, select `Local Intranet`, then click `Sites`, uncheck 'Include all sites that bypass the proxy server'
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3. Check `Local Services` and make sure the Dynamic Web TWAIN Service is listed and Running.
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4. On IE, go to `Internet Options` --> `Security` tab, select `Local Intranet`, then click `Sites`, uncheck 'Include all sites that bypass the proxy server'
4. Check your anti-virus software or any other software that can block local ports and make sure the ports 18622, 18623, 18625 and 18626 are not blocked.
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5. Check your anti-virus software or any other software that can block local ports and make sure the ports 18622, 18623, 18625 and 18626 are not blocked.
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5. Disable all the extensions or plugins in the browser, refresh and try again.
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6. Disable all the extensions or plugins in the browser, refresh and try again.
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6. On your Linux client machine, visit https://127.0.0.1:18626 and https://127.0.0.1:18623 separately in Chrome and FireFox, manually add both certificates to the exception lists.
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7. On your Linux client machine, visit https://127.0.0.1:18626 and https://127.0.0.1:18623 separately in Chrome and FireFox, manually add both certificates to the exception lists.
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7. See the solution [here](/_articles/faq/http-insecure-websites-in-chromium-browser.md){:target="_blank"}
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8. See the solution [here](/_articles/faq/http-insecure-websites-in-chromium-browser.md){:target="_blank"}
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8. Set [`IfCheckCORS`](/_articles/info/api/Dynamsoft_WebTwainEnv.md#ifcheckcors) to `true` in `dynamsoft.webtwain.config.js` file.
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9. Set [`IfCheckCORS`](/_articles/info/api/Dynamsoft_WebTwainEnv.md#ifcheckcors) to `true` in `dynamsoft.webtwain.config.js` file.
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9. Ask the user to grant the local network access permission manually. See this [webpage](https://chromestatus.com/feature/5152728072060928) for details.
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