CEF Application Support

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Posts: 1
Joined: Mon Mar 06, 2017 9:55 am

CEF Application Support

Post by Ragini » Mon Mar 06, 2017 10:00 am

Hi All,

I am trying to automate "cef" application. But I have been getting following error. Please help

"Failed to get or update all DOMs. Make sure that the Chrome debugger port is not being used by another program (e.g. Chrome DevTools).
Process: 'offline-desktop-client' (pid 4520)"
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Posts: 284
Joined: Wed Jan 25, 2017 11:08 am

Re: CEF Application Support

Post by qwertzu » Mon Mar 06, 2017 2:09 pm

Hi Ragini,

Most probably the port was not set up correctly like described in the user guide. Another reason could be that the port 8081 is already in use and needs to be changed.

First, please verify if the application can be accessed by Chrome. Furthermore, check if the port 8081 is already in use:

Debug CEF remotely from Chrome

If you are not able to access the CEF application as follows, there is definitely an issue with the remote debugging port.
1. Open Chrome
2. Navigate to http://localhost:8081/
3. Verify if you are able to inspect the content of the CEF application

Check if port 8081 is in use

1. Open the command line
2. Enter the following command:
netstat -aon | findstr 8081
3. If the CEF application is not running, no active connection should be listed.
If the CefSharp application is running, you should see exactly one connection (

I hope, this will help.